I am actually looking for something similar as well.
How to use a service request offering " Onboarding New Employee " then automatically creating the new user account in AD based on the data captured with the request?
I believe this could be done using Orchestrator as the middleware component which integrates with Service Catalogue request using the AD integration Runbook pack.
Another way I guess would be to perhaps trigger a powershell script which would then automate this as well
Has anyone perhaps investigated, already done this or in the process of setting this up as I would be very much interested to know.