Hey, it just hit me . Since what you want to acchieve isn´t technically the same you asked for in the initial topic (sending different CCs by pressing/depressing a button) you could try something more simple.
Now you want to send 2 CCs by pressing a button and the same 2 CCs by depressing, just with a different value. So I think something like this could work:
In the *.NGC file assign 2 events to one button with a specific range and button mode:
SOLO Track 1
EVENT_BUTTON id=1 hw_id=1 type=cc chn=1 cc=15 range=0:0 button_mode=OnOff
EVENT_BUTTON id=2 hw_id=1 type=cc chn=1 cc=47 range=3:67 button_mode=OnOff
SOLO Track 2
EVENT_BUTTON id=3 hw_id=2 type=cc chn=1 cc=15 range=1:1 button_mode=OnOff
EVENT_BUTTON id=4 hw_id=2 type=cc chn=1 cc=47 range=3:67 button_mode=OnOff
SOLO Track 3
EVENT_BUTTON id=5 hw_id=3 type=cc chn=1 cc=15 range=2:2 button_mode=OnOff
EVENT_BUTTON id=6 hw_id=3 type=cc chn=1 cc=47 range=3:67 button_mode=OnOff
MUTE Track 1
EVENT_BUTTON id=7 hw_id=4 type=cc chn=1 cc=15 range=0:0 button_mode=OnOff
EVENT_BUTTON id=8 hw_id=4 type=cc chn=1 cc=47 range=2:66 button_mode=OnOff
MUTE Track 2
EVENT_BUTTON id=9 hw_id=5 type=cc chn=1 cc=15 range=1:1 button_mode=OnOff
EVENT_BUTTON id=10 hw_id=5 type=cc chn=1 cc=47 range=2:66 button_mode=OnOff
MUTE Track 3
EVENT_BUTTON id=11 hw_id=6 type=cc chn=1 cc=15 range=2:2 button_mode=OnOff
EVENT_BUTTON id=12 hw_id=6 type=cc chn=1 cc=47 range=2:66 button_mode=OnOff
With that button mode and range the button (solo track 1) sends CC15 0 + CC47 67 when pressed and CC15 0 + CC47 3 when depressed.
If this works you wouldn´t need a *.NGR script and you could assign all the button within the *.NGC file.
I can´t guarantee for that though. Like I said, I won´t be home till next week to test this for myself.
my regards