Do yourself a favour and pick-up some insulin pins, I like the (1cc, 12.77mm, 29G ) from wal-mart. I rotate delts, quads and lats with these. Havent tried glutes, but if you're lean enough, shouldn't be an issue.
Hopefully you're pulling from vials, swab the vial, push in the air, and pull out to your desired amount then duck tape the vial upside down with the slin pin already in it to the wall. come back in 5 minutes and it will be full. push out the air bubble n pin.