Hi Jim --
Coincidentally, I'm learning how to use the DSP insertion effects for MIDI song sequencing.
Insertion effects 1 to 20 are controlled by the XG EFFECT2 parameters listed on pages 102-103 of the Data List PDF. Two SysEx messages are needed. One message to select the effect, e.g., US Combo Rich Clean:
F0 43 10 4C 03 00 00 63 21 F7
and one message to assign a song part number to the insertion effects, e.g., DSP 1, Insertion Part Number 7:
F0 43 10 4C 03 00 0C 06 F7
These changes are reflected in the DSP effect assignment dialog message accessible through the user interface.
The Insertion Effect Part Number message uses the value 127 (0x7F) to specify OFF, e.g.,
F0 43 10 4C 03 00 0C 7F F7
Hope this helps with your configuration needs.
All the best -- pj