There are two methods:
1) Transmit On Channel 1 for Part 1, and on Channel 2 for Part 2
2) if you have the computer Editor you can change the MIDI Receive Channel.

If you’re controller can only transmit on a single channel, then you will need to edit the PART’s MIDI Receive Channel, which can be done via computer (Parameter Change messages). Do you have the John Melas Editor? A method to send Sysex to your MX?

You can change and store your computer made edits in the MX. The MX has the same basic engine as it’s bigger siblings (MOXF, Motif) but it does not have the same depth of on board editing... to unlock that level of the editing you need a computer.

The John Melas (third party) MX Tools allows the MX user that wants to get at the deeper level of the architecture to fully edit the MX engine. You can get down to the individual Element level of the architecture, and can create sounds with multiple Parts, complex splits/layers, etc. He has a Total Librarian, Voice Editor, Performance Editor, Drum Editor,... highly recommended for the MX user ready to go deep.

And the beautiful thing is you can NAME and STORE all your custom creations in the MX so you can take just the MX to the gig! Highly recommended...

In the DATA LIST booklet you can see many of the parameters you would see on the front panel of the Motif/MOXF are available only via Parameter Change messages (Sysex). The Editors unlock all of this.

I am not very computer savvy. I have a pc. How do I purchase that editing software?

Thanks Rob Mack

http://www.jmelas.gr/motif/products.php

If you just want to change midichannels I believe it can be done with the free performance editor Vycromx:
http://vycromx.com/