I think you could modify this technique that Ice-Cube outlined for adding the hologram effect in this thread:
Hi Guys, I have just figured how to put this effect in Photobooth as well.
1. Extract HoloGit.qtz from the zip file.
2. Place it on your desktop for easy access.
3. Copy the HoloGit.qtz file to /Library/Compositions - The keyword is *Copy*
4. Go to photobooth in your applications folder and right click to *Show package contents*
5. Navigate to content>resources
6. Drag the HoloGit.qtz file from the desktop to this folder.
7. Locate the file *EffectsOrdering.plist* in this folder
8. Open the file with textedit
9. You should see a number of effects listed in that file. You should see user backdrop 1, user backdrop 2, and so forth in the last paragraph.
10. Replace the words *user backdrop 1* to *HoloGit*
It should look like this: <string>/HoloGit</string>
11. Save the file. Close all folders.
12. Open up photobooth and enjoy your newfound effect.
Hey guys, to delete a backdrop you dragged into PhotoBooth, simply click on it as if you where going to use it to take a picture over it, and then press command+delete. And that's it! Hope that helps. Take care.