Unless you can identify the catalog backup tape, no chance - unless you run -mcontents on every tape to try and identify the catalog tapes from the backup headers. Even this is complex, as you would have to manually create a media DB entry for each tape (presuming a NBU reinstall).
If you can id the tape, easy, you can import the tape, and recreate the DR file (the DR file is simply the header file).
The answer to your question, is not to get into that situation, make sure you have the DR file, copied off, of emailed off the system.
That is the only correct answer. As I said, if you have none of this information you have big problems.
Martin
