[Puke]

there is a good example of this in the Porportions Mod.

to make troops available at the start, edit the tech areas file and change the starting level of troop technology to 1 (or the increase level to 1, if you want them available for a medium tech start). you will also have to change the starting or increase level of the prerequisite tech, which i think is 'construction' but it might be 'industry'

to make infantry, or small troops, you can edit the vehicle sizes file to create a 1KT troop, and edit the components file to create a combination cockpit/weapon for him that masses 1KT.