I am trying to set up automatic provisioning of projects in Agile Central through our ticketing system. We have an SSO application that automatically creates new accounts but does not grant access to projects. We have already set up the WS API to pull a list of projects and project owners into our ticketing system, so the information is all up to date. I haven't been able to find any information on changing project or user accesses through the API.
Sure, there's a fairly comprehensive set of user management scripts in Ruby at GitHub - RallyTools/Rally-User-Management. Hope that helps!