Almost as hard as putting a sunroof in one of my trucks.
Clean hands and tools, and slow and careful are the keys. A very sharp knife helps, too.
I'd suggest making a template first. Then once that's perfect, cut the hole.
Anyone with the new headliner will have to see how they are made. I don't know if they are the same material underneath as the flocked type. If they are fiberboard, this won't work without modifying the Homelink module.
I'm still looking for a paint that better matches the interior, so if anyone has found one, let the forum know. It's gray, but with a hint of tan. The one I used is the right tone, but doesn't have that tan tint to it.