Have you considered making a Dimension Picker Control? A good example is:
closure-library.googlecode.com/g … icker.html
Looking at how the control works, it appears to be clever in design rather than complicated to build.
I need exactly this type of control minus the heavy framework for a project I am working on.
If it is not something that you would entertain, it appears that something like it could be made using some javascript and the dhtmlxwindows control.
Cheers,
Alex