Logic style 'Learn Parameter' button?

disuye's icon

Hi all – used MaxMSP for a few years, but recently got RNBO to make my own VST/AU plugins (and to which this question applies):

Referring to the linked video below – re: the Logic Pro 'Learn Parameter' button (aka MIDI Learn, or control mapping etc. etc.) – how can I create this button's functionality within a RNBO VST?

https://drive.google.com/file/d/1sEUQwNcrV1Jplodf4K0k6JixgQPr-BCR/view?usp=drive_link

Thanks in advance! Dan