I've found a way to make Abe leave the screen while possessing a Glukkon in Abe's Exoddus. I've uploaded a video to YouTube which demonstrates this:
https://www.youtube.com/watch?v=XaEeIRqeRcY
You can move around with Abe off-screen. If you hop, the camera moves up one screen, if you do a running jump the camera moves up to the room where Abe is.