Machinencio, there is a tutorial on how to add units in the Tutorials Section of Civ3 - Creation & Customization. Basically, you have to add the unit graphics to the unit folder, create an entry in the Biq, and a text entry in the Pediaicons.txt file.
Redback, I use Gary Childress' guys for the 60s and 70s. I do have the stuff to make a late 50's soldier, but it will be a while. There's a moratorium in place on all non-WW3 work.