You can use the following system exclusive messages to turn off or on parts in Roland GM 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 56 12 01 01 00 10 6E F7
2 / F0 41 10 56 12 01 02 00 10 6D F7
3 / F0 41 10 56 12 01 03 00 10 6C F7
4 / F0 41 10 56 12 01 04 00 10 6B F7
5 / F0 41 10 56 12 01 05 00 10 6A F7
6 / F0 41 10 56 12 01 06 00 10 69 F7
7 / F0 41 10 56 12 01 07 00 10 68 F7
8 / F0 41 10 56 12 01 08 00 10 67 F7
9 / F0 41 10 56 12 01 09 00 10 66 F7
10 / F0 41 10 56 12 01 00 00 10 6F F7
11 / F0 41 10 56 12 01 0A 00 10 65 F7
12 / F0 41 10 56 12 01 0B 00 10 64 F7
13 / F0 41 10 56 12 01 0C 00 10 63 F7
14 / F0 41 10 56 12 01 0D 00 10 62 F7
15 / F0 41 10 56 12 01 0E 00 10 61 F7
16 / F0 41 10 56 12 01 0F 00 10 60 F7
To Turn a Part On
Part / Message
1 / F0 41 10 56 12 01 01 00 00 7E F7
2 / F0 41 10 56 12 01 02 00 01 7C F7
3 / F0 41 10 56 12 01 03 00 02 7A F7
4 / F0 41 10 56 12 01 04 00 03 78 F7
5 / F0 41 10 56 12 01 05 00 04 76 F7
6 / F0 41 10 56 12 01 06 00 05 74 F7
7 / F0 41 10 56 12 01 07 00 06 72 F7
8 / F0 41 10 56 12 01 08 00 07 70 F7
9 / F0 41 10 56 12 01 09 00 08 6E F7
10 / F0 41 10 56 12 01 00 00 09 76 F7
11 / F0 41 10 56 12 01 0A 00 0A 6B F7
12 / F0 41 10 56 12 01 0B 00 0B 69 F7
13 / F0 41 10 56 12 01 0C 00 0C 67 F7
14 / F0 41 10 56 12 01 0D 00 0D 65 F7
15 / F0 41 10 56 12 01 0E 00 0E 63 F7
16 / F0 41 10 56 12 01 0F 00 0F 61 F7
To Turn a Part Off
Part / Message
1 / F0 41 10 56 12 01 01 00 10 6E F7
2 / F0 41 10 56 12 01 02 00 10 6D F7
3 / F0 41 10 56 12 01 03 00 10 6C F7
4 / F0 41 10 56 12 01 04 00 10 6B F7
5 / F0 41 10 56 12 01 05 00 10 6A F7
6 / F0 41 10 56 12 01 06 00 10 69 F7
7 / F0 41 10 56 12 01 07 00 10 68 F7
8 / F0 41 10 56 12 01 08 00 10 67 F7
9 / F0 41 10 56 12 01 09 00 10 66 F7
10 / F0 41 10 56 12 01 00 00 10 6F F7
11 / F0 41 10 56 12 01 0A 00 10 65 F7
12 / F0 41 10 56 12 01 0B 00 10 64 F7
13 / F0 41 10 56 12 01 0C 00 10 63 F7
14 / F0 41 10 56 12 01 0D 00 10 62 F7
15 / F0 41 10 56 12 01 0E 00 10 61 F7
16 / F0 41 10 56 12 01 0F 00 10 60 F7
To Turn a Part On
Part / Message
1 / F0 41 10 56 12 01 01 00 00 7E F7
2 / F0 41 10 56 12 01 02 00 01 7C F7
3 / F0 41 10 56 12 01 03 00 02 7A F7
4 / F0 41 10 56 12 01 04 00 03 78 F7
5 / F0 41 10 56 12 01 05 00 04 76 F7
6 / F0 41 10 56 12 01 06 00 05 74 F7
7 / F0 41 10 56 12 01 07 00 06 72 F7
8 / F0 41 10 56 12 01 08 00 07 70 F7
9 / F0 41 10 56 12 01 09 00 08 6E F7
10 / F0 41 10 56 12 01 00 00 09 76 F7
11 / F0 41 10 56 12 01 0A 00 0A 6B F7
12 / F0 41 10 56 12 01 0B 00 0B 69 F7
13 / F0 41 10 56 12 01 0C 00 0C 67 F7
14 / F0 41 10 56 12 01 0D 00 0D 65 F7
15 / F0 41 10 56 12 01 0E 00 0E 63 F7
16 / F0 41 10 56 12 01 0F 00 0F 61 F7