This isn't really the place for this question. Your best bet is to try
www.cobaltss.net
The guys on there are really helpfull, and I bet they could provide the information you need. And since Im a member, Ill take a look and see if I can find the diagrams for you.
EDIT:
Heres the pinout for the radio
http://www.cobaltss.net/forums/showthread.php?t=2823
If your looking for a "remote" wire for the radio, you can use any wire that has power only when the key is in, just use a circut tester to find one.
As for the antenna, Im 98% sure there isn't an adapter for your application
Hope this helps!