Hi reetp,
First of all, we recommend you to use OSClass 2.0 (it's still RC3, but we're going to release the final version very soon).
After that, you could use the plugin "Extra Feeds" (extra feeds plugins 2.0 is for OSClass 2.0, but you could download a previous verion of it). With that plugin enabled, you could perform any search, add the parameter "&sFeed" at the end of the url and have a feed for that search (you could personalized it, having specific categories' items, or within a specific price range for example).
Then that feed could be integrated in the output of any other website. But we took note about it, and we'll work on some kind of widget to integrate OSClass' items in other pages.
Thanks for the feedback!