What AI Scripts do you run to simply, make the computer opponent, play like they were playing a free-4-all on Use Map Settings?
I give them a command center, 2 SCV's, and minerals. And have tried many different AI scripts, but 1 of the SCV's just mine the whole time, or 1 mines and 1 builds a CC, and then does nothing.

Firstly the regular starting conditions are 1 main building, 4 scvs and 50 minerals.
Preplace the units, set the minerals via triggers.
Then you need to remove randomize start locations in the forces settings as it would screw the comp's player settings.
A comp player must have a defined race, the correct buildings/workers for his race and the correct ai executed.
Try insane ai (cheating) or custom level ai for most challenging opponents.

ok, i did exactly that and i will tell u exactly wut hapens.
3 of the 4 SCV's start to mine
after going back and forth like 10 times, 2 of the 3 mining stop and sit at the command center
the 1 left, continues to mine, and that is all
Also, while im here, is there a way u can choose wut color each person is, instead of them being completly random?

Obviously you haven't disabled randomized starting locations.
Ai behavior and color will return to normal if you do.

Here's Blizzard's explanation of the AIs:

http://battle.net/scc/faq/aiscripts.shtml

I don't know how much of this stuff has changed since it was written, but the themes remain the same -- custom AI is meant for melee. If the human player isn't going to be building a base, it will probably be better to use one of the campaign AIs (like insane): unlike custom, the insane AI doesn't depend on what the human player is doing.