The resulting rom.bin file should be the exact size of your ROM SIMM.
Under OS X, there really isn't any setup or installation to be done. The programmer presents its self as a Communications Device Class (CDC) USB device, aka modem or serial port. No separate driver installation is necessary. When connecting the programmer, System Preferences may launch telling you it found a new network interface (modem). Whatever you do at this step is fine (canceling or accepting) and won't affect operation of the programmer or its application.
Programming the ROM SIMM
Obtain the ROM SIMM programmer application here