Searched around for modules, i've found dx_sale_line_delivered which works perfect for v6.1 and v7(with minor changes)
But for v8, since the new WMS introduced, line.move_ids has been removed? Code extracted from dx_sale_line_delivered:

class sale_order_line(osv.osv):

_inherit = 'sale.order.line'

def _delivered_qty(self, cr, uid, ids, field_name, arg, context=None):

move_obj = self.pool.get('stock.move')

res = {}

for line in self.browse(cr, uid, ids, context=context):

qty = 0

for move in line.move_ids:

if move.state == 'done':

qty += move.product_qty

res[line.id] = qty

return res

Any advice on how to migrate this module to v8? Thanks