I used the clam shell idea when putting together both forearms and the biceps, i can slip the forearms on just without opening them but usually do a little and there is no way i could get them off with out doing so. The biceps go on and off ok without undoing them but its just incase i build myself up ( like thats going to hapen soon, ive been a salad dodger for most of this year, lol)..
I have the glued part at the front and velcro part at the back as not many people really look at you closely from behind.
Thats the way i would do it, depending on your size and the kit your working with