Here is my $0.02. I am by no means an expert but this one of my favourite fisheries of the year. Late November and December are when I head out for this...the rivers are quiet, lots of birds and wild life around, not too cold, ect. Happiness.
5wt is a perfect rig. I use a 10' 4wt sometimes as well.
Look for spawning salmon or spots where fish were spawning, you want to fish downstream of that point. As the salmon eggs wash up the trout gobble them up. Also the trout like peices of salmon flesh from the decomposing bodies. Ideally there will be some old salmon, walking pace water with a few feet of depth, and some structure (i.e. logs, big rocks, ect.).
You can nymph egg patters (glow bugs or pegged beads), with or without an indicator. Indicator is the most effective method but some consider it cheating. Not the most fun to cast either. If you can see an egg or two in the water try and match the size and colour...sometimes they can be picky, other days not. I have found pink or chartreuse eggs work best for me.
When I use an indicator my rig is floating line to about a 9' leader (8lb test) with indicator to swivel + 1.5' tippet (6lb test) then fly. Adjust your indicator depth so your fly will be near the bottom (note that the fly floats up). You want your fly to tumble down the bottom of the river like an egg would naturally. If you see your indicator go down or twitch, assume its a fish and set the hook!!!!
If you hook a salmon, break it off. Don't think that you can land it on a 5wt and it will swim off to go spawn successful; it will likley die from exghaustion. The flies are cheap, let it go.
If you get sick of egg patterns you can use flesh flies. You can dead drift or swing these in the same type of water. Usually I use a sinking line for this.
If you need gear, I strongly recommend going and talking to the guys at M&Y. They will hook you up with everything you need and give you some good info.
Let us know how it goes! And of course if you have any more questions