How to style a treeview in Expression Blend

(Using Expression Blend 4 RC, Silverlight 3)

I have a treeview with several different item templates for different levels. When I o开发者_高级运维pen this project in Blend, it seems I can only really style the top-most DataTemplate (via right-click the TreeView in the Objects/Timeline view, Edit Additional Templates->Edit Generated Items (ItemTemplate) -> Edit Current).

How do I drill down into the level I want and edit those templates?

Rob

A while ago I wrote a tutorial on styling a TreeView in Expression blend. Maybe it'll help.