This should give you the full (absolute) path to the patch, but it might not work if you call it from a Max Collective (or Application, which has a Collective inside).
If you’ll make a standalone you should check the [standalone] object. The attribute "usesearchpath" set to 1 creates a search path of all subfolders of the folder containing the application. Inside that folder should be the files the application will refer to.
Is this what you were asking? If not please give more details.