Yes, I think that this is possible. A problem arises that say, take your basic cube, get into edit mode (edge select) and ummm just rotate the cube so that you can see all of the edges. Go ahead and select an edge. Now hit the Nkey. You should see a whole new drop-down. Under transform you will find info about your edge. Also, turn your widget thingy on, this will help to explain (I hope).
Okay, just for fun now, please note that your transform widget thing is at the median point of the edge, that is to say, in the middle. Alright, let us scale this edge along a particular axis. We do know how to do this right?
Then as you watch the N panel, You will see values changing under the transform panel. Oh yes you will! Now, the interesting part is that you can enter directly any of the values you see changing. Just use the Shift key while in that field.
Hope this helps a bit.