Custom counter cache

class Category   has_many :tracks end

class Track   belongs_to :category, :counter_cache => true

  named_scope :converted, :conditions => {:converted => true}   named_scope :active, :conditions => {:active => true} end

I want to make custom counters for scoped associations, e.g:

category.converted_tracks_count category.active_tracks_count

And when `track` changes its converted, active, and category_id status counters must be updated.

Any suggestions?