From a Visual Studio console application, I right-clicked on References, selected Add Reference from the popup menu, clicked the Browse tab in the Add Reference dialog, and navigated to
C:\Program Files\Reference Assemblies\Microsoft\WindowsPowerShell\v1.0
I then clicked on System.Management.Automation.dll, clicked the OK button, and it added the reference to my project.
Granted, this is probably not the CTP3 DLL, but you get the idea. Make sure you have a reference copy of the desired DLL somewhere other than the GAC for adding the reference.