I have answered this question three times this week on several forums, so I'm just going to copy and paste it this time. They are all pre-wired, as far as I can tell. My 2.5 base coupe (that isn't prewired for anything it seems) even was.
I did not take pictures of the install process; but I do still have the old pieces that came off, so I can use them as an example. Each side (radio & cruise control) are wired together in the same harness, so when you order them you'll get a new set of cruise switches in anyway. Hence why everybody should be prewired.
To access them, disconnect the neg. terminal on the battery since you'll be working around the airbag. Once its disconnected on each side of the steering wheel on the back side you'll find two plastic caps that just pop off to reveal a screw on each side. Simply unscrew these and the airbag will become free from the steering wheel. You can either disconnect the harness from the back of it and take it in the house for the rest, or leave it on if you wish to work form inside the car. Also you'll need to disconnect the cruise control harness (since you're removing it). Looking at the back of the airbag you'll see that it has a flange around the sides where the switch shrouds (the silver trim) screw onto the airbag itself. There are two phillips screws holding on each side, simply unscrew the old ones, screw on the new ones, and reinstall everything in the reverse order! That's it!
If you have the time and want to check for yourself before you order, this whole process takes 5-10 minutes. Just disconnect the battery and unscrew the airbag and take a peek. Hopefully the pictures (especially the back side will help it make more sense). It is a super easy swap out. I purchased them off ebay but you can find them on all the online parts stores. It's listed under the cruise control switch.
One last reminder, for some reason if you leave your battery disconnected for an extended period of time the alarm will go off when you reconnect the battery. So as a precaution if you're going to take your time doing this, pull the fuse for the horn so you don't have a heart attack or go deaf when reconnecting the battery (It might just be my car that does this, but it's happened twice for me).
If you have anymore questions just ask.
Sorry their huge, I did cut them in half, but I still wanted there to be some detail.
The easiest online store to find them is Courtesy Parts. Just drill down through to the cruise control switches. There are four different part numbers for the switches. The cheapest one with the least amount of notes is obviously the base model one that you have (25550-L32001), the (25550-L32002) Looks to be what you need, it shows as optional for the 2.5 and standard equipment for the 3.5 (which the basic audio controls are standard on 3.5's), (25550-L32003) looks to be the assembly for the blue-tooth controls (for the TEL reference notes), and (25550-L32004) looks to be the switch set for navigation equipped models since it has the longest set of notes, and the highest price. So for clarity I am 99.9% sure that you need part# 25550-L32002. I'm sure you could call Courtesy Parts and give them the part number and ask them if that's the correct set, they might give you the "you can't add options that didn't come from the factory speech," but obviously you can since I did.
Also I take no responsibility in any damages you might cause to yourself or your vehicle in attempting this, I can only tell you what I was able to safely do.
If you have anymore questions just ask. I know this thread was long, but I copied and pasted most everything from the other posts. I need to ask someone to add this as a sticky lol.