I googled it up and they are available and with instructions. Just google, pinky pump. I attach some rubber tubing to the end so its soft on the snake. You can get that clear rubber tubing at most hardware stores, I also cut the end of the tubing so it slides in the mouth easily.
Also, start of with a tiny bit, and work up. Again, Force feeding should be a last resort. With a mentally and physically injured individual, this tool may be of help.