I have some basic partial pedaling working. I can get the release time to change according to the CC64 value, and it continuously changes using ampeg_dynamic=1 as you suggested. That's cool!
Now, I need to set three ranges, for example when CC64 is: range 0-32, normal 0.8 second release. Range 33-64, variable depending on number. Range 65-127, full sustain (or we can just set to a full 10 or 12 seconds).
Can this be done with custom curves? "locc64=33 hicc64=64" doesn't seem to filter out below 33 and above 64.
The GUIs, that's not public, and the main XML for each instrument bank needs to be digitally signed by Plogue, but they'll do that for free for non-commercial instruments which are half-decent. You can contact them if you want the documentation and example files.
Just to necro-post on this: I've modified the GPO5 instrument bank XML file, and everything seems to work. I've added extra instruments that I've created, and changed which GUI xml files the instruments are assigned.
Interesting! Maybe the GPO ones are signed differently. I know a couple of my older freebies broke when uploaded to Github which either added or stripped out a linefeed from three older XMLs edited using some specific editor years ago... so they can be real sensitive.