But all calibre does is to use operating system functions to copy data to / from the device.
And while yes you can downgrade calibre to a much older release, the majority of plugin authors do not provide old versions of their plugins.
What you could try is downloading a portable version of calibre into a new location and try it out (ie not touching your main install).
All versions of calibre can be found at
http://download.calibre-ebook.com/