Agent Assignment in Task Definition - getting rid of general tasks!

[Susan R. Keohan]

Hello all,
 
I am trying to get rid of the 'general' assignment for some workflow tasks,
as the experts have informed me that this will improve performance.  I want
to change the agent assignment in the task definition to the standard role
(which is also specified in the multi-step task in the 'agents' field.) SAP
doesn't seem to want to let me specify a role of type AC; in the 'choose
role' pop-up box, I can choose roles of object type AG but that's all.
 
Can anybody shed some light on what I am missing here ?
 
Thanks
Sue