Actually Greg,
It sounds like you already have it all figured out
For drilling up into a wall plate at the ceiling, you could use a long auger bit.
Cut a slot in the wall wide enough to accept the bit and drill at a slight angle.
A good electrician can run an auger bit into a wall and angle it to cut it's own slot in the drywall.
As you said, you're inside a closet, you can get away with a little bit of experimenting there