Mark IV channel switching

[avoelp]

I have a Mark IV B that I want to use with an effect module that has two programmable relays. Is it possible to switch between the Mark IV's three channels using only two relays (e.g., Rhythm 1 should be active when both relays are off, Rhythm 2 when relay 1 is on, and Lead when relay 2 is on)? How do I have to set up the external switching jacks to do this?

Andreas