Control the pololu USB servo controller 16 on Mac (or Linux, or Win (may require add'l work))
http://www.pololu.com/catalog/product/390

basic code via pyusb site
http://sourceforge.net/projects/pyusb/
http://pyusb.sourceforge.net/docs/1.0/tutorial.html

with some additional help from USB in a Nutshell http://www.beyondlogic.org/usbnutshell/usb1.shtml

Based on my previous work using pySerial (linux), but updated for pyusb (mac, etc.) posted original code sample here:
http://forum.pololu.com/viewtopic.php?f=16&t=535&start=0&st=0&sk=t&sd=a