How do I make OneShot do what I want?

New Atreus owner (and old Model 01 owner) here. I would like my Fun key to work the normal way when held and to do LockLayer(FUN) when double-tapped, but I don’t want the regular single tap OneShot behavior.

I feel like this should be possible, but I’m confused by the documentation. It gives an example of syntax (OneShot.disableStickability(OSM(RighttAlt), OSL(2), ShiftToLayer(4))) but it doesn’t describe what that syntax actually does. What do I need to put where to get the behavior I want?