I actually aprove of this request. No so much for the glissando effect but because MIDI plugins in Cubase have rarely been updated and they could do so much more (remembering an old StepDesigner 2.0 thread). Such functionality could add to the score editor, which has all but been forgotten to update. Creating symbols feels like Windows 3.1
Of course you can do this by hand but sometimes “micromanaging” notes is a waste of time when arranging big stuff.
Anyways, until such functionality is added (if ever) I would suggest doing it by hand.
Years ago I had wanted a “strum” plugin, very similar in functionality of course, but how about disabling notes of the glissando, up down, 6 notes, and stuff. Your idea might be simple but extending functionality would make programming the plugin actually worth it.