[Seaside] SUInsertion + SUSortable - Evalscripts needed?

[itsme213]

I have a nested, tree-like structure of items.

I allow SU-insertion of nodes into that tree.

The children of any node (including subtrees) are sortable, including newly 
inserted nodes.

Any sketch of what I need to do this? I have tried a couple of things, 
including trying to sprinkle an #evalScripts: true someplace, without much 
luck. My code is somewhat convoluted, includes a fair bit of domain 
specifics, and is ugly, so I have not posted it ...

Thanks - Sophie