to add to what Phisherman has already suggested, be sure to add a dry
(powder form) defoamer to the carpet... also, i'd suggest doing this:
put like a towel on top of the area with a 50 lb dumbell weight pn top of
the towel, this will force a lot of the soap from the padding into the
towel. if you only try to remove the soap from the carpet, the spot will
return forever (until you remove it from the padding).
btw, alcohol is a waste of time folks. rinse rinse and then rinse (but you
HAVE to force the soap out of the padding first).
use a laundry softner--it reacts with the detergensts to actually to
decrease their foaming--then a wet/ddry vacuum