(Let's keep this clean!!)
What do you mean by this? I think i answered your question, so is this comment clean?
There are a number of things you can do:
1. Get a Apple mouse or pad, that does have a single hand right-click function.
Or - If you have a hardware MIDI keyboard like i understand you say you have, then you can:
2. If the keyboard has assignable controls, then you can assign them to Modulars Fine tune.
3. If the keyboard have a hold pedal, then you can use that to hold a note.
Or - With or Without a keyboard you can do this in Modular:
4. Set VCA release time fully up, then it's a Hold function, and hold the note.
5. Trigger notes by in example using the sequencer or a LFO.
6. If necessary - Fine tune a little at a time without sound.