I've used P&E's USB BDM for some kernel debugging of the previous LTIB release (2.6.10) but it wasn't pretty. Basically, I used an older version of CodeWarrior to break the kernel where I wanted to and then step from there.
I think the latest CodeWarrior has module debug capabilities so that might work for you. Or wait until someone ports the kgdb for MCF547x/8x.
Best,
Andreas