Dude, you are not even gonna believe this, but in the process of writing the above-mentioned blog post I actually figured out how to do it with two ObjectDataSources too.
Part of the reason I didnt see it earlier is that there is a mistake in the MSDN about how and when a bound item is actually available.
I will show both solutions in the blog post.
EDIT: Blog post is now available
. Hopefully this will help others trying to do the same.