I've spent a couple of hours trying to get my LT to change to specific speaker combinations on the PC+ (NOT presets) and finally the only way I've got it working is to follow the method used to make the LT choose a PC+ preset, program that in command centre as a 'Bank/Program' command, and then do a seperate 'CC' command after it.
Command 1 sets a bank command to change to preset '0' on the PC+ (the 'flat' mode) (see attached image)
Command 2 sets a CC command to change preset voicing to '1' (the 'fl solo' mode) (see attached image)
I was unable to get this to work using only CC commands.
I hope this helps someone out there as there isn't much information online (apart from a couple of useful youtube videos and a post on this forum) but for some reason I still couldn't get it working until I tried to combine bank and CC commands, which I hadn't seen anyone suggest before.