While we don't have a "first class" Quality Center integration, we have a number of customers who have done this. Unfortunately, HPQC automation is not easy, especially to generalize into a plug-in, which is why we don't have built-in support for it.
But there are a few general things to keep in mind as you design a process around this, and of course please don't hesitate to reach out for more help :)
Of course, BuildMaster can run "anything" with a commandline-interface using the Exec operation. You can create a Powershell Script to surround this, or a OtterScript module to give you a consistent set of arguments.
Unfortunately, QC doesn't have a commandline, but it does have a COM-based OTA API that can be used to build a commandline tool that BuildMaster then calls. You could also build an extension using the Inedo SDK that calls this API, but in this case, building your own CLI is typically easier, because you can independently test it, and it offers some isolation against problems with the COM-based API.
It does appear that QC has a REST API, but it is a "technical preview" and probably isn't feature complete. You may be able to use it, which would be a lot easier, since you can just use PowerShell or built-in operations to make simple HTTP calls.
Hope this helps a little bit!
