Hi Chad,

This will require some customization of the user interface.

At first you will need to add new permission name to some module (Site Manager -> Development -> Modules -> e.g. CMS Content -> Permission names). Then you need to grant appropriate user roles with this permissions.

Now, you need to modify the user interface source files. You will need to view the information of each frame (the header tabs, link to Site Manager, etc.) and in code behind of these files, there is already a security check for the access permissions. In site manager pages it is checked for global administrator. For example, you will need this kind of IF statement
if (CMSContext.CurrentUser.IsGlobalAdministrator)

to

if (CMSContext.CurrentUser.IsGlobalAdministrator || CMSContext.CurrentUser.IsAuthorizedPerResource("CMS.Content", "<your_permission_name>"))

I hope it makes sense.

Best Regards,
Juraj Ondrus