Uh, no. Don't even try it. Avoid 120v hack jobs like... well, like an electrical fire. It will probably work just fine one time, but mucking about with household current is a REALLY risky proposition. Run down to Radio Shack and get yourself a butane-powered soldering tool. It looks like a fat pen, and it's a handy thing to toss in the toolbox.
Strictly speaking, it's a bad idea to plug a soldering tool into an extension cord anyway.