Ecuador Localization

Hi guys, i have working on a module for Ecuador localization, i need create some field on customers and vendors, invoices and i need create a electronic invoice too ( we have this on idempiere) but how i can extend the core doctype on my module ? i need create the RUC field and contributor type on customer for example, how can put this code on my personalized module ?

Thanks on advice

Hey Orlando

Is your module open source?