If the item has only MAT poses setup for P4, you'll need to edit them to replace the BUM references with one to the JPG file of the same name.

It's a good idea to get into the habit of unpacking content (especially older items) into a temporary directory, so that you can check that everything is in the right place and check for bad or incorrect file references while it's easy to locate all the files that came with the item (or not as the case may be).
Once you've moved (or if you installed) everything in a large Runtime this task gets much harder.