In reply to crux_crusader:
If the holds are good there's almost certainly something you can do with heelhooks, toe hooks, bicycle moves, twisting, inside flagging, drop-kneeing to hold your hips close to the wall and lock yourself into position without working on getting a stronger core.
Robbie Phillips' articles were good for technique tips and training:
http://www.ukclimbing.com/articles/page.php?id=3694