Here are the steps you would take to add MIME Types to your account.
Log into the Customer Control Panel with your main account’s username and password.
Click on “Hosted Domains”.
Select your domain.
Click on “Web Hosting Settings”.
Click on the “MIME Types” tab.
Click the Define New MIME Type link.
Type in the “Associated extension” & the “Content type” MIME Path. (Example for PDF mime type)