Use alcohol + salt, and they should sell pipe cleaners in any smoke shop. Try heating some alcohol in the microwave (be VERY careful when doing this) for a few seconds, then pour it into a ziplock bag with a little salt, and put each part of the pipe in the bag separately and shake it around. Afterwards, use a pipe cleaner to try to wipe off any of the other resin.
That would be the best thing I could think of. But I mean, it's a metal pipe. They cost like 10 dollars in any headshop. You could always just buy a replacement one. I only use metal pipes for on-the-go smoking utensils. And ever since my favorite headshop started carrying little pyrex bats/one-hitters, I stopped using metal all together. Glass is much smoother IMO.
-legz