Own Rule (Role) definition

[Peggy Stammler]

Hello,
 
we are not using HR and I would like to define/program a own rule to
determine the responsible agents for the workflow step at runtime. In the
SAP Glossary and Help I found that this is possible, as well on the SAP
Course BIT601 they said that this is possible, but I can't find how I have
to do that. In TR PFAC I can select Role (rule) definition Type: function to
be executed. SAP automatically fill into function:
RH_SAP_ORG_OBJEC_ACTORS_GET. What do I have to do? Do I have to write my own
function module and insert this here?
 
In principle: Is it possible to write a own rule like: get all SAP users
with role (PFCG) Y_WF_XY_User and Sales Organisation = vbak-vkorg and
replace with this rule the maintenance of an organisational plan? To
maintain an organisational plan is double work for us and we don't need an
org.plan.
 
Thanks for your comments and help.
 
Wish you all a nice, happy and prosperous New Year.
Peggy