Yes, it is possible to turn on and off the GPS100 transmitted messages (or PGNs) using Maretron's DSM150, DSM200, or DSM250 display. On the display:
enter menu mode, scroll to "Configuration..." and press < Enter >
Scroll to "Device Configuration..." and press < Enter >
Scroll to the row containing the GPS100 and press < Enter >
Scroll to "NMEA 2000 PGN Enable/Disable..." and press < Enter >
You will see a list of PGNs that the GPS100 transmits.
Scroll to the PGN that you want to turn on or off and press < Enter >
Use the up or down arrow keys to choose On or Off and press < Enter >