Hello morphius, if I'd tried my usual dark patterns(purple, black, dark green, dark blue etc.) and pink patterns, plus my red/black patterns and my yellow patterns I think I'd be forced to try big dry flies.
Can you see the steelhead? If you can, dry a big orange stimulator...a #4 perhaps, and try dropping it about 8 or 10 feet above the fish and try to get as dead a drift as you can. If that doesn't work, you might want to go to your nearest fly shop or get in touch with a fly fishing club/organization in your area.
You might also be surprised that your state fish and game office if you have one near, may have answers. Oh and you might look around online for a local and more specific bulletin board and you might get offers to meet and try for steelies with someone near you that knows more. Hope some of this helps !
Cheers,
MontanaMoose