Documentation on using PLURAL in Pywikipedia

I understand that Pywikipedia now has PLURAL support. Can someone who knows how the PLURAL support works please put a note of explanation on the project page. We translators need to know how to write the PLURAL code into the messages. Also, can you explain whether we can use PLURAL on any message, or whether we need to request that PLURAL is enabled for particular messages (as we do for MediaWiki).