How to reinstall cover on post between front and rear doors?

I pulled the top of the cover off looking for a place to mount a passenger handle. Looks like a sturdy seat belt anchor that might work. But my big question right now is how to get the cover back on? It looks like there are tabs that go under the door gasket. Thought it might just snap back in place but no such luck...

 

It should just snap back in. There's all kinds of clips, just gotta make sure they're lined up with the right holes

 

Nope. That's what I thought would likely be the case but here are the tabs. Looks like they tuck behind the gasket.