Absolute position vertices in UV editor?

[Sirisian]

Nova, thanks for the tab trick, but it only does offsets. I think micheus summed up where I'm stuck.

I'll explain the issue in more detail. Say I have a rectangular prism. I select a face and project normal. I can move the object to the bottom left so the bottom left vertex is at (0, 0). The issue is I don't know where the other vertices are so I can't even offset to place them at exact coordinates. (Well the top left will be at (0, 1) and I know the y position of the other ones since it takes up the full height for the rectangle).

One way I guess I can hack it to work is to resize the area into a square then project normal and move the vertices from there, but it's obviously less than ideal.