I finally got a response back from Lulzbot, and they sent me to where you had already pointed me.
Finally got a chance to work with the code last night and so far it’s exactly what I needed for my Taz 6 ( to keep the single extruder config but enable the second extruder port for cleaning, building, testing other extruders ). Changes that I needed to make were confined to Conditionals_Lulbot.h and were fairly simple & straightforward ( maybe 5 or 6 lines #define ’s ).
When I don’t have a second extruder connected to that cable ( V2C @ https://itworks3d.com/product/lulzbot-taz-4-5-tool-head-wiring-harness/ , $35 ) I have to put a thermistor across pins 15 & 16 or Marlin aborts with a min temp error, but I had several Semitek therminsters on hand so that was no big deal. Octoprint gives me convient access to both toolheads ( and it was a trivial change there to enable the second toolhead ).
Looks to be a very useful hack for me, and I’ll report back here if I have any particular problems with the software ( and/or my hacks :).