The dimmer should be fine. Just be safe with your wiring dont leave stuff exposed.
I've also seen wall plugs that let you switch between something like 1.5v, 3v, 6v and 9v at radioshack. I forget the actual voltage numbers but i think thats close, something like that might be worth checking out.
Good luck and be safe!
Primary: Soon to be lots and lots of cider
Kegged: Strong Scotch Ale
Bottles: Grape Peach Wine, Grape Raspberry Wine