XML from SQL dump?

I have given up my attempts to fix the problem preventing me from signing in in to my admin panel (described here http://wordpress.org/support/topic/if-this-forum-doesnt-work) and have decided I need to move the posts from there to another existing WP blog of mine.

The trouble of course is that I can’t get to the admin panel to save an XML export file. I can get into myphpadmin and save the entire database but then there’s the problem of getting those posts into the other blog.

Anyone know how to generate the required XML file?

Alternatively, how I can generate an RSS import file from the old blog, because the feed is still working and I’ve adjusted it to include all posts. The Codex says that an RSS file can be imported but not how to create one…