Hi Pb1
I don’t know when or if this function is going to be implemented, but maybe you can create your own function to replace the Arduino one. Take a look at this link http://arduino.cc/en/Tutorial/ShiftOut#.U1BKD_ldVHU in there is a tutorial of how does the shift out function works and a couple of examples and just in case http://playground.arduino.cc/Code/Function this a tutorial about how to write functions. I hope this works for you.
Regards
JPMontero_Intel.
