As you write, PM is a Visual Studio add-in only for the moment. This
means that it cannot work outside of Visual Studio. This is due to the
fact that it relies on the object model exposed by VS to collect the
page methods defined in your code.
I'm well aware of this limitation, and I'm currently thinking on how
PageMethods could be made standalone, and become available as a command
line tool. This will require removing the dependency on the VS code
model and using a custom C# (or VB.NET) parser instead. This change
will require some time. Stay tuned...