[169indy]

I Used the "Lloyd-Chick" Trick.
Medium sized staples, straightened out and cut to length re bend insert and fold over.

It is a bit difficult to do a one person install, you also need to pierce the rubber and use a small pair of round nose pliers to "Roll" the ends to simulate a mechanical-stapler crimp.
With practice and time it can be done in a manner to replicate a factory installation vice the repop square body roofing staples supplied.