Masking

What have you guys done to Mask around scenic pieces? I have a show coming up where the scenic looks like a dialogue bubble. Hippo has the 'Live Masking' which would be perfect for this, and I have not seen anything in Catalyst that does this. Any thoughts?

It depends on how complicated the mask is. For rectangular-ish things you can usually get away with a mix window and a black box. If it is more complicated, load up photoshop in fullscreen mode and draw a mask, save as a jpg and use it as a mask. Not anything special but it does work.
You can also use a curved mix window for this if you need to finesse it into place.

If you have the CAD file of the scenic object and it has been cut by CNC machine, then you can make a mask from the CAD file.