Personal Stock Streamer registers a global COM object that may be accessed from other applications. The name of the object is "PSSScript.PSSScriptModule", and it may be retrieved (from VBScript or VBA) like this:
Set PSSObject = GetObject(, "PSSScript.PSSScriptModule")
From a Win32 application, you can use the GetActiveObject() function with the CLSID {EFECFCFF-B3FF-4960-9822-AA9E3FC1D4A0}.
Note that the PSSObject retrieved is actually a "pre-object" that represents the top level scripting module. When you use GetObject() from an external application, the Application object is not registered in the global namespace of that application like it is when Personal Stock Streamer is running the script directly. So in order to get the Application object, you must get the Application property of the global COM object like this:
Set Application = PSSObject.Application
After you get the application object you can access it just as if the code was running directly under Personal Stock Streamer.