[Postman]

I don't get it, the aux approach works, but why prefer it over my suggestion? Break LCRs into a stereo pair with mono center. This gives you surround panpots on all three signals with two faders. The stereo track's panners can be linked to make panning toward the rear even easier, or unlinked to do anything you want. You may not want to pan center toward the rear at all, or you might want to pan ONLY center fully to the rear and leave the stereo pair fully front. Whatever sounds best. No aux faders, full control.

One other benefit is no extra latency to the rear channels that auxes introduce, and I believe dsp useage is the same either way.