Hi,
The only way to provide permissions in DSpace is via the methods I mentioned in my prior email (in this thread). There is not currently a way to create a new group and tell DSpace to give it permissions *across all of DSpace*. Permissions can only be assigned Community by Community or Collection by Collection.
The only global groups at this time are "Administrators" and "Anonymous" and there is not yet a way to add new global groups.
Hopefully that helps explain things better.
Tim