yes. matman's trick was specifically to give a on/off switch instead of a pedal.
my video shows how by default, the MFC XP 1 is already controlling Output 1 volume (CC#10). if you changed things, to get it back there watch my first method in the video with the volume block where i attach the modifier to External 1 (CC # 16) just have your expression pedal control CC#10 or 11 (out1 or out2). you will be turning down your reverb and delay trails too though.
if you want the same pedal to control both out1 and out2, i'd suggest changing out2 CC# to 10 as well in the Axe's I/O Control screen. so both out1 and out2 will use CC#10 and assign the pedal to #10 as well. (i don't usually recommend changing the Axe Control page settings, but it's the only way to accomplish this task.)