I have tap set up via the exp jack on a musicom so possibly I can help. I also have bypasses set up.
I'm using an EFX III+ but this should be the same.
Procedure I use to set up a bypass.
On the space:
-Rcv Channel (in my base) set to 3
-Rcv Ctl (basically assigning the CC number you're going to use. This isn't the MIDI channel. Say C10. Doesn't matter which. So bypass is set for C10. (Another example, my Line6 M5, controlled on Channel 1, uses CC#11 for bypass toggling. I can't choose. On the eventides you can.
-On the Musicom, Press and hold the mode switch to get into the PC/CC programming. Toggle PS-1 to choose which loop you want to send the CC. Say LP.1
– Press PS-2 and the display should read C.01. This is the MIDI channel. Since in this example I'm on MIDI channel 3, bank up to select c.03 and store it.
– Press PS-3 and the display should read "—" This is the CC#. Bank up to choose 10 since we set the space to have bypass on CC#10 in this example. Store it.
– Press PS-4 and the display will read "nor". Bank up to select "rEv" so the eventide toggles on when Loop 1 is active. Store it.Show More...
So there is your bypass set up. Whenever you turn on Loop 1, the space will be active.
Same theory for setting up the expression pedal via the musicom. I think the problem is your confusing MIDI channel number and CC number.
– On the space. MIDI channel is still set for 3 as above.
– RCV CTL – Go in and scroll to whatever knob you want to control. Say mix in this case so scroll to Knob0. The display says the CC# for this knob is 22. So that's ok. Leave that.
On the Musicom:
Press and hold Mode to get into the PC/CC programming.
– Press PS-1 until the display reads "ESL"
– Press PS-2 and the display will read "C.xx" Bank up or down to set to C.03. The MIDI channel the Space is on. Store it.
– Press PS-3 and the display will read "—" (or whatever CC is currently assigned). Bank up or down to set the CC to 22 since that's what the Space has the mix knob tied to. Store it.
And you're done. The exp pedal is now varying the mix from 0 to 100.
Hopefully that works for you.