FileRouter Custom File Type Name?

You'd have to register the file extension with a UTI to make it work. FileRouter is triggered when LaunchServices tries to find a default handler for a UTI, e.g. net.daringfireball.markdown. Registering a new UTI is a bit of a pain, but if you figure it out, you can then just drag a file with that extension to the menu bar and configure it like any other file type.