writing properties is not as straightforward. You basically need to append them to the page, but how would you specify where, also formating,etc. If you don't really care about the readability of the page, you can just extend the current api to by a function(name, value) that appends [[name::value]] to the page text.
But there is not standard solution.
From: Mike Travers <email@example.com>
Sent: Mon, May 24, 2010 11:19:35 PM
Subject: [SMW-devel] Write properties into wiki?
I'm trying to find a way to programmatically write properties into a SMW through an API, just as I can read out properties as RDF. I just want an API that takes a page, property, and value (or values) and stores it. There seems to be no convenient way to do this. Am I missing something?