fori,
Yes, it can be done. The tile contractor will cut under the tile and remove it. The biggest problem is dirt and debris staining the existing plaster. They just need to spend a little extra effort to keep the mess to a minimum.
After the tile is installed, they will caulk the bttom and top of the tile or it the case of coping they may mortar the top joint.

Thanks for the reply, GG.

Can I go with a poured concrete deck/coping on an old pool? Ummm I don't know what it's called--where the coping is integrated into the deck instead of being prefabbed chunks. Seems messy...

Am I going to have to drain the pool for tile and all that? Maybe next time I'll think through this a little better before I start!

Cantilever deck. Yes you can do that. In that case there is no mortar between the tile and the deck. I guess it could be caulked. My builder used forms from Mortex that includes trim called a cove strip that covers the joint between tile and the deck to allow for movement there without exposing a gap.

Thanks, BP!