WillAtlas, if you haven't found out already, catching a steelhead on a fly is akin to a hole in one in golf. There are some great books to get you started. The one by Trey Combs, and another by Deke Myers are very helpfull. Depending on the water conditions you can use a floating or sinking line. Shooting head systems are a good way to go for winter steelhead, so you can match the water conditions. You will need a heavy leader. I like using 12 pound test flurocarbon. Flies come in all colors of the rainbow. Purple seems to be a good color for steelhead for some reason. I like to use big bunny leechs and wooley buggers. If you really have your heart set on catching a steelhead on a fly I would recommend hiring a guide. You will learn more in one day (with a good one)then you will sludging away by yourself. Good luck,
-Steve