Starkeeper,

What is your 'Roland' ?
Why do you want to send a GM-ON command from an external device ?
I would expect the Roland to have at least some buttons and there is a way to set the GM to ON. with the help of a manual.

As far as I know Pro-tracks IS a sequencer-program, so I do not understand your question

SYSEX-messages can be recorded and played back with sequencers. Most sequencer-progs e.g. Cubase have an option to read/build or edit the messages by hand (hexadecimal numbers)

You can merge the message to midifiles, to be sure the 'Roland' is in the right GM mode.

Roel