I suppose if you've just got a 100% and you don't have long enough sheets to let the sail out to their proper angle, you could have lee helm. An over trimmed sail, with all of its effort forward of the mast ought to push the boat to leeward.
On my boat, I like to run the sheets through the fixed leads on the deck. This is for my 135% genoa and it creates a nice shape that helps in the lighter winds we usually have here. We sailed yesterday and my wife noticed white caps as we were heading out, so we hove to and put a reef in the main, but left the genoa leads up, rather than putting them through the cars on the track. With the reefed main and the full genoa, the boat sailed very well, with the expected bit of weather helm.
I hope you figure this out- there's nothing better than heeling over and feeling the boat gripe a bit, reminding you that she's got your back and won't let you go over.