Currently there is not a 'points' system in the module. The rankings, as you know them in the module, are simply based on post counts (which you as the admin can control which post count equals which ranking). I am currently investigating how outside modules can be utilized here (ie. integration) without having to include all type of functionality (like a points system) within this single forum module where it is not beneficial unless the entire portal takes advantage of it. For now though, I can't think of any way you can do this based on the current module 'out of the box'.