You should be able to get that allen wrench at Home Depot; that's where I got mine. Be forewarned, it's kind of expensive and you have to buy a whole set of them (or at least I did). I think $40-50.

Do you have a way of getting the front wheel off the ground? If not you can get a stand or you can build your own using pipes and straps (that's what I did) all though this option only works if your bike has a center stand.