Hi
yes B12 can be helpful IF you are deficient in it.
B6 seems important too as well as the B8 - Inositol.
B5 (pantothenic acid) seems to help teeth/jaw tics
most people with TS do benefit from all the B vitamins but many find it better to take them separately or as part of a general multivitamin, rather than as B-complex. Some people like to get their Bs from bees (ie honeybees) by taking Royal Jelly as a supplement. It is an excellent source of other nutrients too
there is a thread stickied here where I have outlined my son's initial treatment plan.
We started that in 2001 so he is has adjusted it a lot since. Mainly gets the nutrients from food and teas now rather than as capsules/tablets. I need to update it again.
http://neurotalk.psychcentral.com/thread1145.html
The magnesium form that seems to get most positive reports from TSers is the plain Natural Calm that is ionic magnesium citrate (we get ours at iherb.com as usually least expensive, altho the Vitamin Shoppe stores sometimes have it on sale as well)
another helpful way to get tic relief is via Epsom Salts, used as a full body bath (2 cups in warm water tub, soak 20min) or footbaths (1/2 to 1 cup epsom in warm water) depending on size of foot spa or basin
there is a very good book discussing natural ways to treat TS
http://www.latitudes.org/book.html
http://www.petergillham.com/wp/2009/11/natural-calm/