You can use the following system exclusive messages to turn off or on parts in Roland GS sound sources. You will need to input and send these from a sequencer that allows you to create SysEx messages from scratch.
To Turn a Part Off
Part / Message
1 / F0 41 10 6A 12 01 00 10 00 00 6F F7
2 / F0 41 10 6A 12 01 00 11 00 00 6E F7
3 / F0 41 10 6A 12 01 00 12 00 00 6D F7
4 / F0 41 10 6A 12 01 00 13 00 00 6C F7
5 / F0 41 10 6A 12 01 00 1C 00 00 6B F7
6 / F0 41 10 6A 12 01 00 1D 00 00 6A F7
7 / F0 41 10 6A 12 01 00 1E 00 00 69 F7
8 / F0 41 10 6A 12 01 00 1F 00 00 68 F7
9 / F0 41 10 6A 12 01 00 18 00 00 67 F7
10 / F0 41 10 6A 12 01 00 19 00 00 66 F7
11 / F0 41 10 6A 12 01 00 1A 00 00 65 F7
12 / F0 41 10 6A 12 01 00 1B 00 00 64 F7
13 / F0 41 10 6A 12 01 00 1C 00 00 63 F7
14 / F0 41 10 6A 12 01 00 1D 00 00 62 F7
15 / F0 41 10 6A 12 01 00 1E 00 00 61 F7
16 / F0 41 10 6A 12 01 00 1F 00 00 60 F7
To Turn a Part On
Part / Message
1 / F0 41 10 6A 12 01 00 10 00 01 6E F7
2 / F0 41 10 6A 12 01 00 11 00 01 6D F7
3 / F0 41 10 6A 12 01 00 12 00 01 6C F7
4 / F0 41 10 6A 12 01 00 13 00 01 6B F7
5 / F0 41 10 6A 12 01 00 1C 00 01 6A F7
6 / F0 41 10 6A 12 01 00 1D 00 01 69 F7
7 / F0 41 10 6A 12 01 00 1E 00 01 68 F7
8 / F0 41 10 6A 12 01 00 1F 00 01 67 F7
9 / F0 41 10 6A 12 01 00 18 00 01 66 F7
10 / F0 41 10 6A 12 01 00 19 00 01 65 F7
11 / F0 41 10 6A 12 01 00 1A 00 01 64 F7
12 / F0 41 10 6A 12 01 00 1B 00 01 63 F7
13 / F0 41 10 6A 12 01 00 1C 00 01 62 F7
14 / F0 41 10 6A 12 01 00 1D 00 01 61 F7
15 / F0 41 10 6A 12 01 00 1E 00 01 60 F7
16 / F0 41 10 6A 12 01 00 1F 00 01 5F F7
To Turn a Part Off
Part / Message
1 / F0 41 10 6A 12 01 00 10 00 00 6F F7
2 / F0 41 10 6A 12 01 00 11 00 00 6E F7
3 / F0 41 10 6A 12 01 00 12 00 00 6D F7
4 / F0 41 10 6A 12 01 00 13 00 00 6C F7
5 / F0 41 10 6A 12 01 00 1C 00 00 6B F7
6 / F0 41 10 6A 12 01 00 1D 00 00 6A F7
7 / F0 41 10 6A 12 01 00 1E 00 00 69 F7
8 / F0 41 10 6A 12 01 00 1F 00 00 68 F7
9 / F0 41 10 6A 12 01 00 18 00 00 67 F7
10 / F0 41 10 6A 12 01 00 19 00 00 66 F7
11 / F0 41 10 6A 12 01 00 1A 00 00 65 F7
12 / F0 41 10 6A 12 01 00 1B 00 00 64 F7
13 / F0 41 10 6A 12 01 00 1C 00 00 63 F7
14 / F0 41 10 6A 12 01 00 1D 00 00 62 F7
15 / F0 41 10 6A 12 01 00 1E 00 00 61 F7
16 / F0 41 10 6A 12 01 00 1F 00 00 60 F7
To Turn a Part On
Part / Message
1 / F0 41 10 6A 12 01 00 10 00 01 6E F7
2 / F0 41 10 6A 12 01 00 11 00 01 6D F7
3 / F0 41 10 6A 12 01 00 12 00 01 6C F7
4 / F0 41 10 6A 12 01 00 13 00 01 6B F7
5 / F0 41 10 6A 12 01 00 1C 00 01 6A F7
6 / F0 41 10 6A 12 01 00 1D 00 01 69 F7
7 / F0 41 10 6A 12 01 00 1E 00 01 68 F7
8 / F0 41 10 6A 12 01 00 1F 00 01 67 F7
9 / F0 41 10 6A 12 01 00 18 00 01 66 F7
10 / F0 41 10 6A 12 01 00 19 00 01 65 F7
11 / F0 41 10 6A 12 01 00 1A 00 01 64 F7
12 / F0 41 10 6A 12 01 00 1B 00 01 63 F7
13 / F0 41 10 6A 12 01 00 1C 00 01 62 F7
14 / F0 41 10 6A 12 01 00 1D 00 01 61 F7
15 / F0 41 10 6A 12 01 00 1E 00 01 60 F7
16 / F0 41 10 6A 12 01 00 1F 00 01 5F F7