When we want to trim the headsail from the windward side we take a turn around the leward winch and then over to the windward winch. We call this cross sheeting.

On the C&C 115 I race on we have main sheet winches either side of the cockpit with a double ended sheet. You can trim from either side. Sometimes you have to even out the tails but it works really well most of the time. I think you can only do this with a 2:1 reduction, not sure how to make it work with more.