Policy documentation normally comes from within. Any policy which may not be suited to your site due to culture difference, drafted by an outsider, you will find it difficult to implement in your floor level.
The best way would be to make a policy which is adaptable for your site. You are the best judge and draft, also ask your (HR) reporting manager, all customer departmental Managers to right a policy for your firm Finally if you want you can give it to an external agency to compile the same ( within the legal frame work requirement).