RD Services 2012 change from Per Device to Per User

I am deploying a new RD Services 2012 server and purchased 25 Per Device CALs.  I realized that I should have purchased Per User CALs and I would like to know the procedure to change this before I go live.  Do I have to call the Microsoft License Clearing House first?  Do I use "Edit deployment properties" to change the licensing mode or do I also have to modify the local policy?

Thanks in advance

Rob Walker