Quoted from SideTrackTap:I've never done it personally, but a buddy just runs speaker wire from the sub in the cabinet to a powered subwoofer usually placed under the game. Mind you, the key word is "powered" subwoofer.
Others with more experience might be able to offer more information.
Chris
Nope, you nailed it! Although I do recommend soldering the wire connections instead of aligator clips. Powered subs (many pinheads love the Polk 10" powered sub) add a great fun factor to games. I actually just picked up a TFLE yesterday and need to do this! 
GLWS! Fun game.
