You will need the following things:
-wire for tying: pre tinned copper wire, I used 32 guage, you could probably go a little thicker, but I wouldnt do much. Radio Shack is where I usually find this. Theoretically any thin wire that will hold the solder will work, but this is how it has always been done, so this is what I use.
-Solder: Its better to use a low temp solder as it will expose the spokes to less heat stress, which in theory would be bad for them. I have used high temp silver bearing solder, and it looks great, but is a pain as it requires a higher heat not always attainable with low grade soldering guns.
-Flux: thick paste flux is best as it stands up to heat better and will let the solder flow really well.
-Soldering Gun: just about any will do, but I like to use at least a 40W gun to keep the job a bit quicker and easier.
-A Bike Wheel: can't tie and solder a wheel, without a wheel, now can we.
-This Instructable: well...duh.