Can we have fonts that are able to read from a text (or similar) file for their spacing?
As you can see, I've already done it before. It really was quick and easy, and I'll give you the c++ code to make things go more quickly for you if you like. Because of the way c-script deals with fonts, it is currently difficult (and ineficient if you did) to do this.
The important thing is that you have a tool that generates a file with the apacings listed.
An example of such a tool is Bitmap Font Builder,
Link. Poor old Thom is giving this program away for honesty donations. Perhaps you could talk to him get this technology integrated with 3DGS?