Existing posts and comments were easily migrated i.e. export from MovableType and import in WordPress, that’s all. The challenging part was retaining permalinks of posts published using MovableType. I didn’t have to do anything for monthly-archives beacuse the url-format being used in MovableType was exactly same I chose for WordPress so I just removed old directories (created by MovableType).
Category and individual archives’ permalinks were taken care by putting some code on top of MovableType templates for those archives. So request still goes to old archive pages, where code on top constructs the new wordpress page URLs and redirects there. Which means I am going to maintain old MovableType installation (at least php pages) until I figure out other way. This bit is tricky because MovableType generated filenames (permalinks) in very inconsistent manner, perhaps due to configuration issues back then.
Feed permalinks were taken care by simple rewrite rules in .htacces. Over the time, I would be fixing the look and feel of the blog and other minor issues (line-breaks and all that). Please let me know, if you find any broken links (from your bookmarks) on this blog or any other things. I would appreciate that.
I could share the code and .htaccess stuff here, but it’s not really very clean. I would do it once I am done figuring out a better of doing category and individual archives’ permalinks handling. However, if you really want to see the stuff, please leave a comment and I would send you whatever I have