It doesn't address your question directly, but I think it's a decent effort : when the real data's ready for zipping, make them run LFNBAK and include the resulting LFNBAK.DAT file in the archive.
I wish I could find the appropriate options for it, but I don't have access to the install CD now.
Oh, or have your vendor get software made in the last 6 years. But you did mention budgetary problems.