This should be possible with the midi/in/script object, but you'll have to write the code yourself to do what you want.
You can find all the necessary documentation in the firmware code:
You will need to call the MidiSendSysEx() function. The uint8_t bytes in that funtion will contain the data for the SysEx message.
More info on how SysEx messages for Roland machines are constructed can be found here: http://www.2writers.com/eddie/TutSysEx.htm