Also try heat sinks, or alligator clips. I can't think of enough tools and tricks to hold a part in place as you solder it. I took a bullet for a part once on the old Lion Roar Halftrack, couldn't get the part to stay in place for nothing so I held it with my finger and hit it with the micro torch...burned yes, but growing up in a restaurant I had worse burns. But the part got soldered!! (I don't suggest this as a method to solder parts)
If you use any sort of vice be sure to put the part sandwiched with wood, that way the metal mouth of the vice doesn't act like a heat sink. Unless you want it to act as a heat sink...Really, rigging up the jigs to hold parts is as much an art form as any of the stuff we have to do in our little hobby.