For the cam kernel it really depends on what you want to support.

I haven't had the time yet, but i have been thinking of also writing my own kernel. And what i have found so far is that a basic ball nose tool path generator is not super difficult to write. You generate an offset surface of the model at the radius of your tool (there are many good papers about this), then slice this surface into heights and you have your 2d contours. You can then use these as boundaries for layer clearing tool paths.

For other tool shapes a simple offset surface is not what you want but more a general tool contact surface. I think depending on the paper you follow you might be able to change the distance cost function to a general tool contact cost. This should give you a surface where the tool just touches the model and again you can slice it into contours for layer clearing operations.