I'm making use of the functionality noted below from the manual (specifically the nuance described in blue which no longer seems to work) - A CC sent beyond the value of 3 always sets the target block to chD now, where as before, a CC value sent with a value beyond 3 would select the applicable target block channel based on the sequence (CC#4 would set the block to chA, CC#5 to chB, CC#10 to chC and so on all the way up to CC#127 to chD.
p46: (Ax3 Owner's Guide)
"CHANNEL SELECT
This uses the value of a controller to select a specific Channel. Each block has its own dedicated setting for channel select, found across the listings on the Channel page of the MIDI/Remote menu under SETUP.
The Channel is set by the value of the controller (not the controller number itself... see FAQ below). Values begin at 0, which is Channel A, and it continues from there. (See table 2, right). As with Scene Select (above) the series continues, repeating Channels A–D across values to 127."
I've been using this for a long time to send a hi value to outboard gear that will only respond to OFF(0) / ON(>63) while at the same time setting a specific channel on Axfx.