Transaction Cost Extension -- Actual Cost Hook

 Can anyone provide a business case example, and or sample code for use of the cost management -- transaction cost extension and how to configure the actual cost hook.  Documentation on metalink and web is minimal, and several people have been asking same questions.

We are average costing organization, and using a custom from to trigger WIP API's for non-standard job creation, wip issue/move, manual resource charges and then wip assembly completion.  We are placing wip assembly completion on cost hold, until final costing is determined by the business.  Our custom form relates one or more non-standard jobs to a master number.