Hi Mike

While it will be relatively easy to connect to your Motif via Midi, arrangers tend to have limited Midi control features, (Yamaha being particularly poor) although the Korg are normally quite comprehensive.

Fortunately the Motif has excellent Midi capabilities, (Another advantage a Workstation has over an arranger) so you will be able to boost the arranger Midi features by doing a lot of mixing/switching work via the Motif.

Not sure how well you are up with Midi; however here is a tutorial to get you going,

Happy experimenting

Bill