Yes, it is possible to set permissions on a per user basis using the concept of Permission Classes (i.e. set permissions for each class then assign each user to a class).  

Steps: 

1. Log in as the Admin for your account.  

2. Go to "Account", "Manage Users", "Edit Permission Classes" to create/edit Permissions classes, and mark the appropriate checkboxes of Actions/Features that each class should be able to perform or access.  Click Save.  

3. To add new users, Go to "Account", "Manage Users", "Add User" to invite new users, while selecting the desired Permission class (i.e. User Type) for those users.  Click Add Users.  

4. To edit existing users, Go to "Account", "Manage Users", "Edit User Permissions" to select the Permission class for each User.  Click Save. 

Hi guys,

Yes, this is possible, but only available for our enterprise customers.

- Andy