Have you tried to send the global LFO to a CV Out, plug a jack between this output and the the Pedal In, and control the parameter with CV In ?
First, thank you for your explanation of PAN MODEL / PAN EXP / PAN MOV from GS. If I understand what you wrote, the dynamic modulation allows you to go between different panoramic model settings from "neutral", and I can see how I could use an LFO to automate that (I honestly haven't used the River Key at this point but I see from the manual how to attempt what you describe above).
I was hoping I could just set the individual voice pan settings on the PAN page, and then modulate those with the LFO relative to the initial settings, without trying to figure out the PAN MODEL. If I can find a PAN MODEL that matches how I would pan the voices, and then map LFO to pedal as you describe above, and map dynamic modulation from pedal to PAN EXP or PAN MOV, I should be able to get movement of widening and flattening the stereo image. I don't think I would be able to get movement of the entire stereo image left and right. I could simulate it by only having voices on one side of the stereo field and then modulating as above.
Off to experiment :-D.
EDIT: Did my experiment. I found that if I patched the global LFO to the expression pedal input and DYN SRC to CC11 EXPR, nothing happened. If I patched the global LFO to Pedal 2 and the DYN SRC to CC4 FOOT, then I could get some modulation going. It wasn't really gradual movement in the stereo field so much as abrupt movement from left to right channel, but still kind of cool. The problem I ran into was that Pedal 2 has to be mapped to either start the arpeggiator, enter the shift key, or "EXT". If I set it to either of the first two there are obvious problems, if I set it to the third then any chord I held down would die out in a few seconds regardless of my envelope settings. But I can play shorter notes, or run an ARP, and have it work this way. My guess is that the LFO is disabling the sustain pedal periodically.
