Were there are any other ways other than registry access to find the printer attached is a real printer or file printer.
Not with JS. The only thing you can know about it is its name.
Is there any way to do this with a pdf plugin?
Or Is this possible with Adobe livecycle?
You get the system device and path name. So you would need to know every virtual printer that prints to a file and that probably is not feasible.
Some possible non-paper printers:
(1) Microsoft XPS Document Writer
(2) Microsoft Office Live Meeting 2007 Document Writer
(4) eDocPrinter PDF Pro
(5) Adobe PDF
Regarding a plugin ask over at the Acrobat SDK forum.
Regarding LC ask over at the LiveCycle Designer forum.