Payables Holds Resolution Workflow

Customer requires to use the holds resolution workflow to route matching price holds to the buyer and matching quantity holds to the requester. The seeded workflow routes everything to the requester - ever though the approver group returns both buyer and requester. Is it possible to set up a custom workflow to route holds according to our requirements rather than amending the standard holds resolution workflow - and if so, what steps are required to fire a custom rather than the standard workflow from the invoice validation process.

Many thanks.