Sidechain with ANY compressor

larry, you can use parameter modulation to do this. Define the track with the compressor as 4 channel, create a send to it with the controlling audio signal coming in on channels 3/4, set up parameter modulation for the threshold using audio source 3/4.

Thanks nicholas, I'm just sure it won't work on certain comps without thres knobs. Like 1176's and certain op compressors. Man, I think the only way to do it is to use 2 stereo comps and fiddle with mono routing???

Not super related but useful nevertheless :) You can now link one effects paramters to anothers using "parameter modulation" and then choosing the "link" option. This would allow you to set up two mono compressors (or even 2 stereo compressors for surround work) and be able to control as many as you want on the same track from just one of them. Very cool! Just thought I'd mention that!