So I spent a an hour (all I had) playing with it last night. There is a case of multiple instances (which I guess is kind of obvious) even with BaseInteractionTuning.GLOBAL_AFFORDANCES (when called from cheat prompt at least) but my approach (in my case its for a sim interaction but it could be applied to XML appending as well) will be iterating objects at start and when added, then modifying as needed.
If I'm remembering right, the code that generates the pie menu looks at the "super_affordances" flex method to get stuff, so that's a helpful place to poke around. For the XML appends, you might need to extend/copy some of the tuning functions to read a specific file - I didn't look too much at that.
(If anyone thinks what I'm saying is err... less than intelligent? .. please let me know, any pointers would be handy, I'm a fairly experienced developer but I'm learning Python on the fly here so saying something stupid or missing an important detail would be quite easy).
