What you described is how to use the optocompressor as a limiter. I would work from the other direction. Start with the compression ratio at 1:1, the attack as high as possible, the release as fast as possible, and the threshold (slope) at maximum, and turn it on. Guess what? Even though the compressor (theoretically) is doing *nothing* at these settings, you will hear the effect of the optocompressor being used solely as a filter, in other words, a tone shaping device, rather than a dynamic control. If you do this with, say, an RNC, there will be virtually no change, but a Joemeek compressor is a whole different animal.
Then set the attack much faster, and the release longer. Set a moderate slope, say 3, and begin to increase compression. I think you will learn more by slowly squashing the signal than you will by starting with a signal that's already crushed out of existence. In tracking, compression is something I use when I have to. I have on many occasions, used the Joemeek compressor just as a filter, as I described in the beginning. The settings I gave you in my first post above are settings that have been found to be OK for tracking a dynamic vocalist.-Richie