1.Hot glue
2.Epoxy
3.Super glue
4.Bondo
5.Chewing gum
6.Small magical elves holding things
7.Toilet paper wedged in the case to hold it.
8.Gravity
9.Magic
10.Tiger Woods
you will find it VERY difficult to apply abs cement nicely without using you finger.
with all that aside, I personally think abs would be the best choice since after a while hot glue weakens a lot and pops off sufaces with very little pressure.
Apply it with a Q-tip. Dip it in , let a bit drip off and then lay it where you need it. Piece of cake, no mess, cheap, and throw away when you're done.