Nick.

The pattern or desired look dictates the hook. Most of the more "modern" steelhead flies (intruder, hobo spey, pick yer pocket, etc.) are tied on either clipped long shank hooks, spinner shafts, or Waddington shanks with a stinger hook loop that your hook of choice can be hitched into. I use octopus style hooks in a few sizes for the stinger/trailing hook on these flies.

For the classic spey patterns, Alec Jackson's seem to be the standard and are hard to beat for style. The McNeese Heron hooks are very similar and equally classy. These traditional hooks are designed more to make a pretty fly than they are to hook and land a fish functionally though. If function is what you are after, stuck to the stinger/trailing hook design.

To get rolling, your mustad streamer hooks should be fine, just clip the hook off at the bend and you've got a nice shank to wind up your fly of choice on. Up eye, down eye, straight eye, it matters not. For the stinger loop, 50-60lb power pro, dacron, or wire all work just fine. I've been digging the Senyo's Intruder wire recently but have used braid for quite a while with good results.

Ill see if I can whip up a step by step on a basic EP Intruder pattern I've cranking out this week when my new point and shoot arrives tomorrow.