To clarify my earlier post: (I can see now how it may have sounded a little dangerous)
If you have two unused breakers, cut your power at the main breaker (hopefully you have one at the meter panel), yank out the two seperate breakers and install a 2-pole breaker in their place. Then you can run 3+1 (red, black, white, bare ground) to a new 240V recepticle. The red and black go into the double throw, the white to the common bus (the strip in your lighting panel with all the other whiteys on it) and the ground to the ground bus. On the other end, wire your 220V as described on the instructions in the packaging of the outlet. Start your wiring at the outlet and work your way back to the panel - connect ground first, then white, then the red & black.
If you have any doubts or haven't wired anything before, call some electricin out of the phone book. You can possibly get someone to come out for $50/hour.
Good luck.