We can give out root access via an RSA key, but it is typically best for us not to. If we give out root access it is very easy to mess something up. Our DNS settings are very specific. However, something he probably would need is phpMyAdmin access, which we have and there is no problems with him using it if he is qualified. With our DNS setup, even someone qualified could easily have issues. Because of this, for any sites you need added to your server, it's best to send to us and it is a simple process for us to add it for you. If you have and can send a long list all at once that is best. If there is any other needs for root access let us know and either we can describe our method for doing it, or provide the needed access for you to do it yourself. If it is something that we don't have a specific method for then we have no problem to give you access but prefer to know what is going on (many things we have our own method for).
Go to "Manage Resources" (/admin/manageresources) and click on the title of the resource you want to edit
Select a membership from the dropdown and save changes.
After adding the first membership you can add additional ones.