snap in one dimension

Blender 2.54
First of all, how to do this without any add-on, is it possible? I have a lot of vertices and I would like to align them with one particular vertex but only in X dimension, leaving Y and Z unchanged. So I selected this vertex, snapped cursor to it and then what? If I now snap all vertices to cursor, they will snap in all dimensions.

The second question is about using a plugin, but this is my first plugin and it is related directly to this problem, so I post here. In user preferences, I have checked the check box to use add-on “3d view: Align Tools” (maybe this is the solution to my problem with aligning). But after studying the Align Tools wiki page for this add-on, I still cannot find the tools in Blender interface, neither in Toolbox panel on the left nor in transforms panel on the right… Where should they appear?

have the cursor at the vertex, select the other, press period (.) or change snap to cursor. Then scale them in X to 0.

Alright, thanks a lot!
According the second question - where are Align tools addon, I cancel it - found them in Object Mode (I previously thought they are in Edit mode).