Patching and Plastering - Plaster ceiling - hole

I had some water damage to a plaster ceiling, causing a small hole to form. Right now, we have about a foot diameter hole in the ceiling. Even though it is plaster, I can't see any lathes underneath the plaster. How can I fix this hole? It doesn't have to look great, as we'll be wallpapering over it. Yes, we're planning to wallpaper our ceiling. :eek:

Easiest thing to do would be to patch with drywall. If you are not lucky enough to have framing in the right spot to nail to you can take 1X2 strips and set them above the ceiling and screw them to the plaster where ever you can get a good bite and then attach the patch to the 1X2's. finish as you would any drywall patch. Make sure where you meet up with the plaster that the plaster is sound and nut dusty [you may need to prime it] take it slow and don't try to rush it and it should come out fine.

One other thing is that the new drywall may or may not go flush with the exsiting ceiling. It would be good to shim to flush before finishing.