Depends. Look at position 61 on the BCM harness. If it is populated by a gray wire, you should just be able to put the wheel in and have someone with a Tech II flash it to ON for you. If you go to the dealer, make sure you pretend that you had cruise all along and it just stopped working (Play dumb), otherwise they'll try telling you your BCM is incompatable or some other bullshit they've tried telling other members (I believe GM is telling them to not let anyone retrofit the Cruise control in...). I know for a fact that it'll work when wired up and turned on. The dealer I went to were skeptical of it and I told them to do it anyways, then they were surprised when it worked (This was in the G5.. and I already had the stuff pre-wired, so it was plug and play pretty much outside of the reflash).
As long as the wiring is there and the pinouts for the steering wheel harness are correct (They are discrepant between certain years... try to get a wheel from your Model Year. Failing that, get the wiring diagram for your specific vehicle and repin it as necessary), you should be able to have it turned on. If you don't have the wiring, pre-done, you'll need to run it from Pin 61 to your clock spring for it to work.
Generally, if you have power windows and the MP3 capable radio, generally Pin61 should already be populated.
---------- Post added at 04:24 PM ---------- Previous post was at 04:20 PM ----------
From my understanding it depends on the car. I have an LT and all the wiring is there so all I would have to do is just find a wheel and use it. One other thing though if you do have the wiring you have to get the computer flashed to enable the cruse otherwise it won't work. if you dont have the wiring already you would have to use an aftermarket setup.
Not having the factory wiring doesn't require an aftermarket kit. It just requires that he go to a junk yard and harvest a few of the BCM and clock spring pins to wire it up himself.
Anyways, I do have a link that goes into this in greater detail if you need to add the necessary wiring, but I'll have to send it to you off the forum since it is on CSS.