Hi SAP Legend,
there isn't a workflow to request roles via ARM. You can set up a workflow within BRM for role approval. Means that role creation / modification requires an approval from the role content approver.
The request for a new role has to be given outside the system and then someone (e.g. role architect) has to create and specify the role in BRM. As soon as the role is defined the approval can be sent out.
Also it is possible to have the approval stage very early in your process, like after basic definitions of the role. Please find more about BRM and its workflows in the following document: AC 10.0 - Business Role Management
Hope this helps.
Regards,
Alessandro