Project Server 2010 - Users management - RBS code

Hi,

we're currently preparing our Project Server 2010 for our users. Each user need to have a defined RBS code.
Is there a way to set the RBS code programmatically?

I've some experience in PowerShell and do not fear C# if it's not over complicated.
Or maybe there is a command line tool that can to the job for me?

Thanks in advance

Ruben