Long Now is doing something like this but with a nickle disk instead of stainless and etching and electroforming instead of engraving. It allows much smaller features vs engraving. They're engraving 13000 pages about 1500 languages onto a small 3inch disk.

http://rosettaproject.org/disk/concept/

That's a good choice. Laser-marking stainless steel sheet is a common operation with modern laser cutters. That should last thousands of years. It will survive water, fire, and handling.