Here's an update.
1) I've changed the name of the file to better reflect what's going on.
2) I've cleaned up the demo code a lot.
3) The TextOptions object is central to this whole effort now. The TextStyleRange support is just subset of the (eventually) complete support.
4) There is still not support for creating a TextItem/Layer from the ActionManager interface. There are some bits (like ParagraphStyles) that need to be fleshed out before I can do that. But using the ActionManager interface instead of going through TextItem for 90% of common operations is my goal. This approach should lessen the memory and performance problems that have been seen when dealing with text from JS.
Some of you may find it useful as it is, mostly because it is the only way I know of to change the font, size, and color of portions of a text layer.
Enjoy!
-X