I've been boxing 3 barbs + monk, barbs are pretty cheap to gear up - Skorn is cheap and powerful.

Ellay has been doing it, it was this thread which prompted me to try it myself.

http://www.dual-boxing.com/threads/4...st-patch-1-0-5

For efficient farming Act 1/2 - MP1, farming Act 3 - MP0

For keys, whatever MP you can handle to improve drop odds.