Modify WO Bom?

[kforanhbc]

Is it possible (and if so, how) to modify a BOM for a single work order? I'd like to edit the work order and delete the standard BOM item and add the substitute part without changing the actual BOM. Sometimes we will substitute a component for one production run because the component called for isn't available (usually paper of a larger size used when correct size isn't available). I know this can be done in other ERP systems. How about here? Thanks.