So I was having a problem with selecting the C.I.S and I was talking to the maker of the mod and he told me

" When you go to the faction select part you will see a scroll bar by it, hold your mouse over that scroll bar and hold left click and at the same time use your scroll wheel on the mouse and it should scroll down "

And in truth that is almost how it is done. What you need to do is have your mouse over the black box with the faction names then do what he said.

I hope this helps.