Where is the MIDI Learn function? How do I assign MIDI CC numbers?

Not all GSi plugins feature the complete MIDI Learn and/or fully customizable MIDI Control Map.

In some cases, there's a fixed MIDI CC map that is pre-definied by GSi and you can find it in the user's manual. And even then, it's likely that not all parameters are assigned to MIDI CC numbers, but only those that we think are important to operate in a live performance when the software is used as a standalone application.

BUT... since these are PLUGINS, all (or almost all) parameters are exposed as automation parameters that can be accessed by the Host program (or DAW), and most modern host programs offer their own MIDI assignment functions, so even if a plugin has no MIDI assignments at all, as long as the parameters are exposed to the host, the host can control them and act as a bridge to traditional MIDI.

So, in that case, once you've loaded the plugin in your favorite host, just use the host's function to map any plugin parameter to any Midi message.