You need to download service manual switching the printer to CMYKMC mode.
Thanks for the info, I've had it in service mode before to do a head alignment so I'm familiar with the sequence. I just didn't know if it was possible to eliminate the Light Cyan and Light Magenta... I bought the machine used so it had been set up already with CMYKlmlc...wouldn't hurt to keep it that way either I guess...
SERVICE MANUAL
https://fex.net/uk/s/rdao2yv
BTW: If you're going to enter to service mode you need to press a particular sequence of buttons.
There are videos on YouTube that shows how to enter to service mode for example:
Although it doesn't mean that XC-540 has the same sequence. You need to try.... and be careful! First read then think twice and only then do.