Standing up a business process management organization

 I'm standing up a new business process management organization in a large (5000+ employee) regional health insurer.  Need to standardize and document processes around transactional nature of business.  Too many chefs right now.  Big cultural changes, land grabs, ownership and territory issues.  Getting ownership of resources and people and respsonsibility for systems and tools to run business area's processes.  Won't own business process decision-making, but accountable for efficient (read: cheap) implementation of decisions through use, reuse and integration of technology tools.  Afraid that we'll be seen as a barrier to things since our primary role will be to say no to things that don't make financial sense.  No structure to prioritize resources at a enterprise-wide transactional level before resulted in many different owners of different vendor relationships for the same services instead of leveraging one vendor for volume services.  Help!