Continuing the discussion from How to use BerzerkRobot class:
Engine\Plugins\SkookumScript\Source\SkookumScriptRuntime\Private\Bindings\VectorMath\SkVector3.cpp has some good examples of hooking up SkookumScript to C++ code.
In theory you should also be able to tag your C++ calls with the same macros used to expose them to Blueprints and then put the SkookumScript plugin into your project's plugin folder and it will generate the C++ bindings. We have not tested this so there is likely to be some initial issues that need to be resolved. Ensuring this works is on our plan so we will let you know when it is tested and available.
In the future we'll also expose more C++ comments and give more SkookumScript C++ API examples and documentation.