When you are an authorised contact, you will be able to head to https://mex.zendesk.com/hc/en-us, and see all your tickets as an end user.
In the top right of this page, submit a request after setting up a username and password (via hitting Sign In). You will be able to view all his tickets submitted in the 'My Activities' section
You can view open tickets in Knowledgebase> User icon> My Activities.
You won't be able to see requests that have been submitted by others unless you are added as a follower on them (via being CC'd in), and from here, you can login anytime:
Remember, you don't have to login to submit tickets- as an authorised user, all tickets will flow through to the Zendesk MEX Support Portal and be automatically assigned to a MEX Support Programmer.