Does the following file exist on your SAP file installation? x:\Program Files\SAP\FrontEnd\SAPGui\sapfewse.ocx?
If so, add it to Visual Studio (or whatever IDE you're using) as a reference. It is basically a class library that contains a bunch of SAP specific objects that will allow you to interact with. It is very effective because it exposes most of what you need from the SAP GUI. We discovered in other attempts that a lot of the objects in SAP were not available.
You're right there is not a lot of documentation on this subject. Below are a few sources that helped me get started:
-Documentation on the API (For VB and javascript but the general rules and objects are identical). Definitely read the portion on the SAP GUI Runtime hierarchy. It'll answer a lot of questions. http://www.synactive.com/download/sap%20gui%20scripting/sap%20gui%2...