check out
http://www.tricktrack.org/forum/
those guys will be way more into helping you with this, also there is a couple threads already dedicated to wheelies that helped me out a ton.
My best advice:
1. use your arms as little as possible to pop up. Use leg power.
2. sit on the very back of your saddle.
3. LEAN THE **** BACK
4. Practice just popping up and falling back off the bike and landing on your feet a bunch of times and that will help you figure out the sweet spot where you can balance the wheelie
hope this helps