Hi john,
I'm not qualified to talk about soldering liposuction, but I can say that my Weller dual-temp soldering gun heats 8-12 Gage wire and connectors in about one second. I think its 120-180 Watts, or somewhere thereabout.

If I were to attempt this myself, I would use a high power soldering gun. Low power will allow time for heat to travel where you don't need it. A torch may or may not do the same.

Good luck, and keep us posted so we all can learn from this experience.