since i still had the problem of the mesh not mirrored properly along the x-axis after using the sculpt brush to complete the model. the suggested workflow above in my previous post is fine if you have not started using sculpt mode and have not encountered mirror problems with the mesh, but for the rest of us that do have the problem of the mesh not being mirrored properly along the x axis after using sculpt mode, and still being able to keep the mesh multires enabled, and not having to add or delete vertices because the UV’s have already been layed out; another approach will need to be taken to fix the mirror problem. however i warn you this is no quick fix 
if your mesh is anything like mine and every level of multires has geometry that has not been mirrored properly you will need to repeat this procedure for every level of multires of the mesh that has the incorrect mirroring.
i am suggesting this workflow because of the current limitations of working with multires of which most applicable to us is the inability to create vertex groups on any level of a multires enabled mesh other than level 1.
1)firstly switch to the level of the multires enabled mesh that you wish to have an exact mirror on the opposite side of.
2)with the multires enabled mesh selected switch to object mode and shift-D to duplicate the mesh
3)hit M on the keyboard and choose another layer (other than the current layer) to place the newly created mesh on
4)switch to the layer with the newly duplicated mesh on it, select the mesh and apply the multires. this removes the multires information from the mesh and bakes the mesh’s current topology. the reason we need to remove multires from this mesh is because we need to delete vertices from it, thereby making it easier to select and move vertices on our multires enabled into thier correct locations (this will make more sense a little later).
5)i am mirroring my mesh on the x axis, so i need to flip the mesh on the x axis. if you are mirroring on a different axis flip the mesh on the axis which you are mirroring on, for example to flip the mesh on the x axis; with the mesh selected hit s on the keyboard to go into scale mode, while in scale mode hit x on the keyboard to constraint scale on the x axis, while in x scale constraint mode, type -1 (that’s negative one either, on your keyboard or numpad) and this will flip your mesh on the corresponding axis. so we now have an exact mirror of your original multires anabled mesh. so we can start to use the vertex positions of our newly mirrored mesh to move the vertices of our multires anabled mesh into thier correct symmetrical positions.
6)switch into edit mode by hitting TAB on your keyboard with the mesh still selected. delete the half of the mesh with the incorrectly placed vertices. in my case since i am mirroring on the x axis, first i switch to the front view then hit a on the keyborad either once or twice to make sure that no vertices are selected, then hit b on the keyboard to switch to bounding box mode, once in bounding box mode i draw a bounding box around the vertices on the half of the mesh with the incorrectly placed vertices.
7)with these vertices selected hit Del or x on the keyboard and choose vertices from the resulting menu. you should now have half a mesh that is a mirrored copy of your original multires enabled mesh.
8)with your mesh still selected hit TAB on the keyboard again to exit edit mode and return to object mode. hit F7 on the keyboard with your mouse over a buttons view. this should take you to the object buttons view. in object buttons view locate the panel called draw and click the button that says Wire. this will make your meshes edges visable even when the mesh is not selected. this will be a useful tool for visualizing what vertices need to be moved on the multires enabled mesh when it comes to moving these vertices around.
9)you are now ready to switch back to the layer with the original multires enabled mesh, so do so
10)select your multires enabled mesh and hit TAB on the keyboard to enter edit mode
11)hit shift-TAB with your mouse in a 3D view to enable snap or snap to grid. make sure vertex is chosen for snap element and snap mode is set to closest.(see vertSnap01.png)
12)this is where the fun part starts! switch to an orthographic view if you are mirroring along the sides of the mesh (left to right or right to left) switch to a side view make sure you are not in perspective view. you might have to hit 5 on the numPad once or twice to correct this. make a selection of the vertices that are problematic in wireframe mode. this simply ensures that you are selecting the same vertices of the mesh on both sides of the plane that the mesh is mirrored on.
13)with this selection active click mesh->scripts->mirror vertex locations and weight. depending on how many vertices you have selected Blender will take some time to calculate which vertices are not mirrored correctly.
14)Blender then makes a selection of all the vertices that are not mirrored correctly on both sides of the model (ie those vertices that are not mirrored correctly and thier correctly placed counterparts). if you are on multires level 1 you can create a vertex group of this selection for later usage. however if you are at any multires level other than level 1 you will not be able to make a vertex group so skip this step and continue to the next step.
15)with your cursor over a 3D view hit ctrl-i on your keyboard to invert the selection. with the inverted vertices selected (ie the vertices that have been mirrored correctly), hit h on your keyboard. this will hide these vertices as you do not need to edit them.
16)if you are mirroring your mesh along the left and right switch to a top or front view, if you are mirroring your mesh along the front and back switch to a side or top view etc. you should have some vertices floating around on both sides of your mesh. select the correctly placed vertices and hide them with the h key.
you now have only the vertices that are incorrectly mirrored active and editable in your 3D view. this is exactly what you want, because now you cannot move any vertices inadvertantly that are in the correct locations.
17)hit TAB on your keyboard again to exit edit mode and go back to object mode. shift click on the layer that you moved your other mesh to in step 3. you now have atleast two layers visable in your 3D view, the layer with the multires mesh and the layer with the duplicate mesh with deleted vertices created in step 2.
18)make sure your multires mesh is selected and hit TAB on your keyboard to enter edit mode. back in edit mode your previous selection of vertices that you hid should still be hidden, the difference is that now you know where those vertices need to be placed because you can see thier correct positions based on the duplicate mesh. it’s a good idea to work in wireframe mode from here on and switch occasionally to solid shaded mode when necassary. do this by hitting the z key on your keyboard.
19)because you switched vertex snapping on in step 11, you can now select the vertices that are not mirrored correctly and snap them to thier correct locations on the duplicate mesh. do this by selecting the vertices one at a time and hitting g on your keyboard to move them, then holding down ctrl while moving them. Blender will snap the selected vertex to the closest vertex in it’s vacinity. i did mention that this was not going to be a quick solution
20)once you have selected and moved the vertices into thier correct locations, unhide the vertices you hid in steps 15 and 16. deselect everything by hitting a on your keyboard (you might need to do this more than once). if you have a vertex group, select the members of that vertex group. however if you do not have a vertex group make a selection on both sides of the mesh where the problem vertices are. make sure your selection includes both the vertices you moved and thier mirrored counterparts.
21)with this selection active click mesh->scripts->mirror vertex locations and weight. Blender will calculate weather the vertices have been mirrored correctly and make another selection. if there are vertices that have not been mirrored correctly repeat the process of inverting the selection hiding the vertices and moving them into position until the point when you run the mirror vertex locations script and blender does not select anything. if blender completes running the script and no vertices are selected your mesh is now mirrored correctly.
hope that helps some one out there! please let me know if you have any question about this process, i’ll be happy to help out if i can (remember i’m still a newbie, myself).
this process definitely does work and yield decent results how ever there is quite alot of work involved. none the less it’s worked for me on my mesh
Attachments
and decide to upload the file it will probably make more sense to do so when the modeling/sculpting is completed.
