Cain - I used ShoeGoo to attach the capacitor both to the backside of the ESC, and to the edge of the chassis. I used a healthy amount of ShoeGoo, and it has never come off.
Old Image, but you should get the point:
http://www.shearracing.com/tsr6/xxxs/losichassis1.jpg
( and no, the rear suspension arm is nowhere near the capacitor, It has plenty of clearance, the picture is decieving from where it was taken. )