Manager Hierarchy Security - allow Write permission for indirect subordinates?

OOB, CRM only allows managers to write to records 1 level deep (only for employees that report directly).

Our requirement is to allow them to write to records at all levels in their hierarchy.

Does anyone know of a way to customize and allow write permissions to managers throughout levels?  We're open to programmic solutions. 

EXAMPLE:

Manager Hierarchy:

• • LEVEL 1:  Sam Smith, Regional Manager
    • LEVEL 2:  Jenny Jones, District Manager
      • LEVEL 3:  Rob Rosey, Sales Rep

Sam Smith can view and edit Jenny's records.  Sam can only view Rob's.  We need allow Sam to edit/write/append to anyone who reports up to him, including indirect employees.

The Position Hierarchy will not work well for us.  How can we enable write permissions using Manager Hierarchy security?

Thanks!