AtomPub server(?) troubles

I’m working on building my own blog editing software. I’d like to use AtomPub since I’ve found Java libraries to interface with my software easier. However, whenever I try and issue a POST request to my blog (http://testbp2010.wordpress.com/wp-app.php/service) I always get a 405 Method Not Allowed. I’m trying to send a post with my username and password encoded in a form. I haven’t been able to figure out how to authenticate to the wordpress.com servers any other way. Is it possible that there is some kind of configuration/firewall issue on my end that is stopping this?

BTW, I know this is the ww.wp.xz.cn forums, but someone said that there might be better support here.

Thanks for your time everyone!