You can buy something called a tick key. We use it on our dogs, but it's designed to pull the tick out head and all. Don't know if it would be safe on a snake, but it should be.

http://www.tickkey.com/

If you leave it it will eventually pull off when it's full but it could just leap onto you or a dog or something and it might start multiplying. You're better off getting rid of it while it's still there.