When you define the library define it ‘withevents’ and then add handlers for the events.
The commnd line sample in openTwain is an interactive prompt (if I remember correctly) but if you look thru Module1 you’ll only see 7 or 8 functions (depending if you count the one that writes out the help).
None of the samples take capability parameters, you’ll use the device’s Ui to configure a device and when you have a configuration you’ll just call the profile by name.