Many different ways to do this, but the easiest is just to use an effect that has ping pong built in. My favorite delay that's a freebie is from interruptor.ch , called Bionic Delay. There's a newer one there that I have yet to try.

http://www.interruptor.ch/vst_donationware.shtml

This should work directly as a VST effect in PG Music products - put it on one of the aux busses at 100% wet, and then use the aux control on the individual channels that you want the delay to select the amount of that delay you want on the track.