I've successfully copied all my posts from the old location. Unfortunately, the internal links and graphics in those posts still point to the old website, so you may have some issues if you follow them. If anybody knows of an easy way in Radio to create build URLs that are automatically relative to the weblog root URL, let me know. As of now I'm using a custom macro.
I don't know the answer but I've been having the same problem. I popped over to Russ Lipton's Radio documention site hoping he might have the answer, but it hasn't been updated since October.