How basic?
You have the M7CL stagemix from Yamaha already I guess? And now you would like to get in touch with the Compressors and racks?
I've tried that on LS9 and 01V, and as soon as the channelchanger feature is enabled to send sysex on more than 16 channels(I only got to the first 16 channels so far) that would be possible i guess, not easy, but possible. Since the reverb and compressor controllers are mostly only adressable as sysex I recomend that you "read" the conversation from Studiomanager to youre mixer. but be shure to disconnect the reply, or you only get a lot of realtimemessages.
I don't see why you would have to have a Mackie protocol for programming the M7CL mixer. Is there something I missed?
/Sigge