Hi Peter,
I'm trying to remember back to using Forms Authentication by following Dan Attis's excellent two part series articles. I'm sure that the 2nd part talked about having the Shared Services extended over two web applications (one with the windows authentication policy and the other with forms). I'm wondering if you could replicate this and try setting up the import in the windows authenticated shared service. The links are:
http://www.devcow.com/blogs/jdattis/archive/2007/02/23/Office-SharePoint-Server-2007-Forms-Based-Authentication-FBA-Walkthrough-Part-1.aspx
http://www.devcow.com/blogs/jdattis/archive/2007/03/01/Office-SharePoint-Server-2007-Forms-Based-Authentication-FBA-w-MySites-Walkthrough-Part-2.aspx
Hope this helps
Dave
My SharePoint Blog www.davehunter.co.uk/blog