Set Business Process Flow to Finished in a Workflow

Hi,

I have a requirement to set a Business Process Flow to 'Finished' in a workflow but cannot find any way to do it.  The business reason is that a manager needs to be able to "complete" a load of records at once via a workflow.

Is this possible?  If not.. is it possible in code via an action, and if so how?

Thanks for any pointers.