I read this before and couldn't see what was wrong, but I've just re-read the post after your blog and have a thought. With the theme we're setting XPages properties, not dojoAttributes. In this case, the initial property of InputField.RichText would be dojoAttributes. The problem is that property is a complex property, with children <xp:dojoAttribute>, each with a name and value property. I've tried a few variants to get it working, but no joy. But that might get you somewhere.