For another perspective on soloing Marrowgar, see the thread I posted on it here:

HTML Code:
http://www.dual-boxing.com/showthread.php?t=29883


I included the write-up I made for myself on how to do it and what key binds I changed to get it done.

I can attest that following that well-documented strategy works pretty well - I tried it from scratch on team #2 yesterday (they have GSs around 5K) and downed him on my third attempt.

Got another tanking mace that one of my pallies was wishing for, too.