I have the GT-3 manual. This should help you--
-------Direct from the manual-------------------
<Transmitting program change messages>
When a patch is selected on the GT-3, the program change messge that corresponds to the selected patch number will be transmitted. The external MIDI device will then turn to the setting depending on the program change it has received.
GT3<MIDI OUT>------->>> MIDI IN<Triaxis
<Transmitting control change messeges>
The operation information from the CTL pedal,
Expression pedal or the external device connected to the SUB EXP PEDAL/SUB CTL 1,2 jack will be transmitted as control change messeges. This can be used for controlloing the parameters on the external MIDI device.
(You must have the GT-3 and the triaxis on the same channel, or put the GT-3 on "Omni" mode so it will send over all channels)
>>Instructions for mapping
1. Select "4.MIDI" with [UTILITY]
2.Use [PARAMETER] to access the following parameter (MIDI Map Select) in the display.
3.Set the MIDI map select with the VALUE dial.
* When the MIDI map select is set to "Fix," press [EXIT] to leave procedure. When it is set to "Prog," carry out steps 4 through.
DISPLAY---
* * *MIDI * *Program * * Map
* * B#0 * * *PC# * 1-> * *1-1
4. Use [PARAMETER] to access the following parameter (MIDI Program Map) in the display.
5. Use [PARAMETER] to move the cursor to the program change number, and use the VALUE dial to specify the program change number to be received.
*To change the bank select to be received, use the same procedure.
6.Use [PARAMETER] to move the cursor to the patch number, and use the VALUE dial to specify the GT-3 patch number that will correspond to the received program change number.
* The Prest Patch is displayed in reversed indication.
7. Repeat steps 5-6 to complete the program change map by specifying the Patch number that will correspond to each program change number.
8. Press [EXIT] to end the procedure.
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Hope this helps man. if it doesnt they have some more stuff in here but hopefully this will get you on your feet.
-chris