I haven't done it, but this is what I would think you can do.
If you pull the amp off the back of the box you should see they two leads connecting on the sub. I am presuming the subs are in series (i thought I say a post on this, saying 2 - 3ohms in series for a 6 ohm load), so most likely one is connected to the other, and that leaves one cable off each sub to the amp. You can get just a backing plate to run the wires to. You would need to get an external amp to drive it then, otherwise you would have to look at getting a backplate amp, something from like partsexpress.com. Problem with that is sizing, you would need the dimensions of the amp and the cutout on the sub enclosure and get something to match. This would be tricky and might be easier to plate the back up and go with an external amp. You maybe changing the internal volume and thus the sound a bit, but its definately easier to go this route.
As for the rest of the speakers, you can technically hook them up to a regular A/V reciever, again, the ohm rating is a little lower I think, just need to be careful not to overheat the amp. I wouldn't worry about wattage that much, as they should be 60watt speakers, and having a 100watt amp isn't bad, atleast you should get a clean signal.
Aleternatively, if it's like others...this thread might help.
http://forums.klipsch.com/forums/t/90312.aspx I can not vouch, so proceed at your own risk.