I've done exactly this to moderate effect with "greenstuff" modeling epoxy. I use it in my other hobbies and had it on hand. It lacks the strength to really break multiple seals from some of the loctite's used in apple products. (related: http://www.amazon.com/Games-Workshop-Green-Stuff-Modelling/d...)

Usually a tough Allen wrench of similar size and some luck works on those oddball sized heads.