Also see the OHMM WIKI and FAQ.

Prolific USB to Serial Drivers

The provided USB to serial adapter is based on the Prolific PL2303 chipset, which should work without extra drivers at least on modern Linux installations. For other OS you may need to manually install drivers. In particular for Mac OS X we recommend using the osx-pl2303 driver, a binary version of which is included in the driver zipfile:

cd Prolific-Drivers/Mac/PL2303_MacOSX_x86/osx-pl2303

You may get some error messages as the installer first attemps to uninstall the manufacturer’s driver, which may or may not already be installed. This has been tested on OS X 10.8.2 “Mountain Lion”. You can also try the official manufacturer driver.

OHMMKey Virtual Machine Boot Issues