Obviously you'd be using a wiring harness for the power and sound etc. For the steering controls theres plenty of IR based options where u have to drill holes in your cabin to mount it ETC, i reckon thats silly. Assuming your headunit has a 3.5mm jack hole for a remote wire, (my pioneer does) theres a very good option.
For the steering wheel controls you can buy a device called a PAC SWI PS. It works with all pioneer and sony decks. You can say goodbye to your instrument cluster integration.
Ebay it, you can buy it from america for about $80 and wait, or get it locally like i just did for about $170. Very worthwhile.
All you have to do is plug it in there, and connect the RED wire up to a switched 12v source, black to ground, and the white wire to pin C11 just above your wiring harness. C12 you need to ground. I just hacked the wires off the back of the wiring harness(but leave more length than i did to re connect them later!!!) See the link to know what i mean. Your power and sound wiring harness covers the areas where the A and B pins are.
Pac-audio.com Steering Wheel Interface | iPod Integration for your car and More by Pac-Audio - Connecting you to the future
It has some simple programming steps (easier than i thought) and you're away. Just shove the pac device behind where the cupholders or where ever behind the dash and your done!
If you decide to do it and get stuck gimme a buzz. I only had the confidence to do it because another JC member helped me.