The import scripts which come with Gossamer Forum only support importing from UBB5, UBB6, WWWThreads/UBBThreads (Perl and PHP versions), ikonboard, and at a later date, vBulletin. So the answer to your question is no, it can't import from that format. However, you can write your own import script to import this. If you take a look at the existing import scripts, you should be able to write something similar to import your messages.

Adrian