I'm not really sure if there's an easy way to do that, since the SYSEX that Yamaha sends are probably proprietary, and Ketron would not respond the same way.
By digging into the Tyros Data List manual, I found this:
F0 43 7E 00 ss dd F7
ss=- 00H INTRO 1
01H INTRO 2
02H INTRO 3
03H INTRO 4
08H MAIN A
09H MAIN B
0AH MAIN C
0BH MAIN D
10H FILL IN AA
11H FILL IN BB
12H FILL IN CC
13H FILL IN DD
18H BREAK FILL
20H ENDING 1
21H ENDING 2
22H ENDING 3
23H ENDING 4
dd=F7 = End of ExclusiveWhich means that Yamaha sends the following SYSEX everytime when FILL IN AA (as an example) button is pressed:
F0 43 7E 00 10H 7FH F7If you check in your Ketron's Data List manual and the same SYSEX corresponds for this action, in practice it should work strait out of the box, but I really doubt that it is the case.
Sorry if it wasn't very helpful, but at least you'll know where to look at.
Cheers
Valentin