I got a stock 02 bonneville se and wanna subbs in there but wanna keep the stock radio (ive seen it done!) what all do i need to do this??

You need a High to low converter. There are several out there. Rockford fosgate, Jl, audio control just to name a few have their own versions that run upwards of $250. PAC also makes one called an SNI-35. Its less than $30. After that, you will need everything that you normally need (wiring kit, amp... Lol!)

what is a SNI-35 and were can i get that, that sound cheaper then 250? lol

Google is your friend, my young friend. Search for PAC SNI-35. I also got 15 hits on ebay for the same search.

ok hey u should go take a look at my car in the pic tab thing at the top or click that link in my sig. and tell me what u think??

Sweet ride. Looks in great shape.

Look at this link:
PAC SNI-35 RCA Line Output Converter LOC Adapter HI LOW - eBay (item 120456767164 end time Oct-06-09 09:33:07 PDT)

ok so this goes too BLACK_FRIDAY.. so once i get that PAC SNI-35 were do i hook it up? like in the back of the stock raido and run my a.c cords from that to my amp???

you tap the high level side (the wires coming out of the box) into speaker wires, and then run your rca'* to your amp from the female plugs on the other end. You can just tap into your rear speakers. If you are gonna run a mono block, wire both positives together and both negatives together.

so i really aint gotta mess with nothin i the back of the stock raido?

nope. you can get all of your signals in the back of the car if you like