I agree with the first poster - find a Cognitive Behavioral Therapist. This individual should be able a) to give your son some strategies to deal with bullying etc. b) give your son some behavioral strategies to address tic behavior at school and at home and c) give you strategies to take to an IEP meeting so that your son can better manage his tics.
While it is true that many folks with Tourette's do well with medication, most also need some sort of behavioral intervention as well, particularly given that stress can exacerbate tics. Ask the therapist to train your son in progressive relaxation. Hopefully that therapist will provide you with a CD with the protocol so that you can use this technique at home.
Some folks with Tourette's are able to hold back their tics for a short period of time and then they can go to a more socially appropriate location to engage in them. So - if you tell your son that every hour, on the hour, he can tic as much as he wants, he may be able to hold them back. (It might be for a shorter period of time... just giving an example). When folks are able to do this, the tics can be intense for a bit while they "get them all out". You could build this into your son's school schedule. Usually this just works for a short period of time (like a school day or less) and kids need to be able to let it all hang out somewhere else, such as at home.
Also ask if the therapist is able to use purely behavioral techniques, such as habit reversing training - which can help reduce the tics a little.
Finally, find a support group both for you and for him. Parenting a kid with a developmental difference is highly stressful... more so than parenting a typically developing kid. Take care of yourself and stick with the folks that can support you through this, as well as your son. Putting him in a support group will be great for him because he'll learn that there are other folks like him, going through what he's going through.
Here is a site that is likely to be of help:
http://www.tsa-michigan.org/
Call the TSA - they'll know who the good therapists are and they'll be able to help you to utilize the school district's services more effectively. Usually folks are more than willing to help you for free!