Ralf, thanks for posting that link. I thought I remembered that from somewhere. After a little playing around, I figured out the work flow and here it is:
Create a mask on one of your images and then export, then:
Tools > Import > Import Mask then choose
Import masked for: Active chunk
Method: From File
Mask file names: TYPE OUT THE NAME OF YOUR FILE WITHOUT WILDCARDS
Click OK
Photoscan will ask for a folder, pick the folder with the mask you created in it, click Select Folder
Before you know it, you'll have duplicates of that mask on every photograph in your chunk.
Thanks!
p.s. David, thanks for the renamer link. Plenty of uses for that.