Thanks for pointing out that plugin. It might be possible, but I
haven't investigated the plugin fully. From the comments it looks
like several people are having issues making it work. When I
researched collection management in the past, the issue was that you
have to completely destroy and recreate the collections file, and (I
think) actually reset the Kindle, which is a little to heavyweight for
a simple Instapaper management program. I'll keep my eye on it,
though.
Thanks,
James