Install your Zebra
To begin you must have installed your Zebra printer on your Mac.
Go to System Preferences > Printers,
Click the + button to add a printer.
From the Use: list click Select Software... and in the Printer Software popup, select Zebra EPL Label Printer.
Click OK.
Configure your Zebra
Open the 'Terminal' application on your Mac.
At the command prompt, type:
cupsctl WebInterface=yes
and press Return.Find your Zebra printer in the list and click on it.
If a popup Authentication Required appears, enter your computer's admin user credentials.Look for General Options and set your Paper Size to 4x6" (100x150mm)
Click Set Default Options.
Your printer should now be configured to print on 4x6" thermal labels.