I had a similar problem and neither "make him an admin" or using Feature delegation (kept getting an error about a missing configuration section 'wsgi' were working for me.
This is what you do:
Install the IIS Management Service (using Server Manager)
Open IIS Manager
Select the Site you want to grant access to and select the "IIS Manager Permissions" feature. From there, I add the user to the list using the "Allow User..." option.
From the Server Features View, select the "Management Service" feature and make sure the service is running.
Your non-admin user should be able to access the specific website settings from the IIS Manager with his account. Unlike administrators, he won't see the available sites by default the first time around. He will have to establish a new connection to a website by specifying the server (localhost) and the website (as specified in IIS, NOT the actual public URL).
Once the connection is established and saved, it will only ask for the account password the next time you run IIS Manager.
Hope this helps anybody with a similar issue, I had to dig a bit myself to find this solution.