Digitech RMS-1 Tube Rotary speaker simulator

I have acquired a Old rack unit made buy Digitech in 95. It will do exactly what a Leslie will do, Left and Right outs for the upper Horn section and a center out for the Rotor section. It can be controlled by the FS3X foot switch. It has stereo inputs. I am hooking it up two 3 Fender amps. I am trying to figure out how I should hook up my pedals to it in a way that the center rotor section wont receive the effects going to the two amps I am using for the horn section. The only thing I can think of is to put the pedals between the outputs of the rack unit and the amps. But to do it I will need stereo pedals that have stereo inputs as well as stereo outputs and there dont seam to be alot of choices in pedals that do it that way and not any reviews/demo's of pedals hooked up with the stereo inputs in use. So any one running a wet dry wet rig in stereo have an answer for my quandary.