[Koha] Batch edit to control fields?

Hi, All -- Does anyone know if the Batch record modification tool can handle control fields? -- specifically, changes to various positions in the leader, 008, etc. We're trying to update the 008/33 in a large number of records. I've tried creating an action for this under a MARC modification template, but it seems to be expecting standard fields & subfields (i.e., it won't accept a 2 digit number to represent a position). We can always export to MarcEdit, but if we can do this from within Koha, that would be great. All best, Cab Vinton, Director Plaistow Public Library Plaistow, NH