APC40 and user modes for the knobs

Did anyone ever figure this out?  I've been searching the internet to no avail.  I can disable everything, but there's a key difference between disabling the knobs and the buttons that is driving me crazy.  When buttons are disabled, they still respond to messages telling them to light up.  The knobs do not.
I'm sure there's a way, a message to the control or component that will allow me to turn the default functionality on and off while still allowing them to respond to LED update commands, but "getinfo" isn't revealing to me what that command and argument might be.  Has anyone cracked this?