Depends on what you are trying to do exactly.
If you want the hand to snap into place on it then you can setup a spline that you snap to like how the melee base class handles handle snapping.
If you only want it grippable along that section, no real snapping, then you could use a proxy mesh / collision shape along that edge that gets gripped and then is either constrained to the door, or promotes the grip to also grip the door itself (see how the door handle promotes a grip to the door when fully engaged).
You can also do both, a proxy mesh along the edge that enforces a hand position by snapping as well.
Or you could make a custom class that is a grip promoter that gets polled for what to grip instead so you don’t use the grip system on the proxy.