I am a 3 week old rookie being humiliated by my boss because I have a learning deficit as a poor speller. He makes snide comments in front of all the other officers as well. They have discouraged me from using the spellcheck on the computer stating it will take too long. We were recently given a long list of words and was given a "quiz" which I was not told about. I told them of this deficit before going through the academy. So how do I get them off of my back or what alternatives do I have

You're boss probably shouldn't be joining in the fun. Aside from that, I suggest that you develop thicker skin. Don't let the snide comments bother you. Police are a tough crowd. We have each other's back every time, but are just as quick to make fun of one every chance we get. We have at least 2 officers that I can think of in my department that spell practically every other word wrong. We make fun of them because of it. They are both good police officers even though they can't spell! Also, we all should be using spell check!

Suck it up!

Your boss is making a big mistake and by doing what he/she is doing to you could end up getting them reprimanded, very foolish on their part.
Am also a poor speller but have learned in the last 3 or 4 years that reading does and will improve spelling. Start reading more, pick up books that grab your interest and read, read, read. It should help over time to greatly make you a better speller.
Be happy you were hired by a department and work hard to improve your spelling before you know it you’ll be spelling as good as the ones teasing you! Now I need to work on my grammar!
Good Luck
PS Thank Goodness for spell check!