How do I select which tray I would like to print from on my company printer?

I am using a Mac and attempting to print a file from illustrator to the bypass tray of our company printer.  I am personally trying to print labels and I don't want to risk putting the labels in the main tray and have someone else print their document before I can push print on mine. I have done the due diligence of searching the internet for this issue but with no helpful results found just yet. Any advice?