Hi Peter,
I'm not sure if what I did is exactly what you're asking, but I did make an adapter to go from a RJ45 EQMOD cable (made for HEQ5) to the DB9 connector on my NEQ6. I used this backshell from Jaycar with a male DB9 connector:
https://www.jaycar.com.au/d9-female-...aptor/p/PA0906
https://www.jaycar.com.au/db9-male-c...older/p/PP0800
Wiring as per the EQMOD USB method (as I have a USB cable):
http://eq-mod.sourceforge.net/eqdirect2.htm
For some reason my HEQ5 EQ cable used Pin 1 for GND, so I joined 1 and 4 form the RJ45 to Pins 4 and 5 of the DB9.
Again, I don't think this is the answer to the question you've asked but it might be useful for someone else.
Cheers