I just put mine back on the way it came off. If you look on it you'll see holes drilled in different places around it--that's where it was balanced at the factory. The clutch disk--the part that wears--floats, so there's no need to take it into account during balancing.
Martian had some fancy space-age way to balance his and I think he ended up just putting it back on the way it was. Check Slope'rs 'tearing into my PD thread' for it.