Here's how I did it:
I also used stick on lead weights for RC airplane balancing, but I simply did not trust just double sided sticky tape to hold them inside the wheel.
I stuck the weights on where they needed to go and then I used 30 minute epoxy as the final balancing "weight". This also helps to secure the weights in place.
http://www3.towerhobbies.com/cgi-bin...&I=LXK204&P=ML
The fourth picture is what happens after you spend time balancing the wheel and the tire decides to spin the tube inside the wheel resulting in an unbalanced wheel...