[Closed] Access Primitive's creation parameters in c# via sdk

Trying to learn some basic plugin development here, using c# and the c++ sdk wrapper. On the sdk page here it shows how to create a teapot primitve, and it uses the paramBlock to specify the radius of 20. Below that it also mentions that default arguments aren’t passed when coming through .NET. I figured out how to create a plane via the same

object obj = intfc.CreateInstance(SClass_ID.Geomobject, cid as IClass_ID);

approach, but it creates it at 0 width and length, I’m guessing perhaps due to the default arguments issues mentioned.

How do I access the plane’s width and length properties?