Get the PSR 740 instument definitions from Cakewalk's website. If they don't have it, I believe you can find it, email me, and I think I have it. Set up Pro Audio 8 with each channel receiving a separate track from 1 thru 16 (as opposed to midi omni). Assign each track to the PSR 740 as the instrument. Record all tracks and see what comes up. If any of the tracks are wrong, you have to look at your Yamaha manual and see how it assigns midi arrangements to each track.
Let's say Chord 1 is on track 4 (for example) and the arrangement you chose has trumpet. Then if the trumpet isn't sounding on that track and instead you hear grand piano, then you have to manually choose the instrument as a patch for that track on Cakewalk.
Make sure that on global options on Cakewalk you choose patch changes for midi options. You can learn a lot from looking at the PSR 740 manual and the Cakewalk manual. They are both very good manuals.
I hope I could help a bit. There is more info at the unofficial psr 740 website. IF you need the address. I think I have it somewhere.