Install your Zebra
To begin you must have installed your Zebra printer on your Mac.
Do this by going to System Preferences, Printers, then click the + button to add a printer.
From the Use: dropdown, click Select Software... and in the Printer Software popup, select Zebra EPL Label Printer. Then click Ok.
Configure your Zebra
Open the 'Terminal' application on your Mac.
Then at the command prompt, type
and press enter.
Then open a web browser and in the address bar type
Find your Zebra printer in the list and click on it.
(If a popup Authentication Required appears, enter your computer's admin user credentials since this impacts all users on the computer.)
Then look for General Options and set your Paper Size to 4x6" (100x150mm)
Then click Set Default Options.
Your printer should then be configured to print appropriately on 4x6" thermal labels.