Sure you can wrestle your camera's strap through this slipcover... it probably won't even take you very long.  But if you don't have the patience, here you will find easy-attach instructions for your camera strap slipcover.
  1. First, detach one end of your camera's strap.
  2. Attach a key to a ribbon, rope or string that is longer than the slipcover.
  3. Drop the key down through the slipcover, letting gravity do the work for you!  Make sure the other end of the ribbon doesn't drop through.
  4. Remove the key from the ribbon and attach one end of your camera strap to the ribbon.
  5. Draw the ribbon back up through the cover.
  6. Remove the ribbon and reattach the strap to the camera.