I've tried to give a user administrative rights to a single driver
object in eDirectory.
According to the docs:
Driver Admin: This administrative role lets the assigned user manage a
single Driver object. It requires the following access rights:
Browse and Create rights to the Driver object

Read and Write access to [All Attribute Rights] in the Driver object

NOTE:Make sure the rights are inherited so the driver Admin can also
manage the driver’s policy objects.

With the rights above the user was unable to edit the Driver Parameters
in iManager.

Giving the user Supervisor rights on both entry and attribute level
didn't help.

Finally I managed to track it down that the user needed write rights to
the DirXML-ConfigValues on the driver *set* to be able to change the
Driver parameters on the driver!

Any idea why that is needed?
I lose the entire point of delegated administration if a user can mess
up DirXML-ConfigValues on the driver set.