MURF voltage controls - how to build a GREAT foot controler

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I have plans to build a two-switch foot controller specifically for the MURF, and need some input:

1. Tap tempo, just need a standard SPDT momentary switch, easy.
2. Mix/Envelope switch.

The plan is to build the 2nd switch so that it chooses between 2 sets of Mix and Envelope settings, e.g. to go from Env: 5, Mix: 7 to Env: 6, Mix 10. I assume I'll need 50K-100K pots for all four controls, and would like to do the switch with a 3PDT, but have one concern. Can I drive the CV of both controls with one +5V input, or can I hook up both +5V to one terminal and share the voltage, or (gulp) do I need a 4PDT switch to keep both controllers separate?