I had really hoped the backs of the cards might help illuminate their origins a bit better, but aside from the usual biographical details and statistics, there's nothing terribly useful here. The backs have a decidedly Donruss flavor to them, with the card number in the baseball icon in the corner, and maxing out at 5 years of "statisticas" (which I think is more Spanglish than Spanish. That should probably be "estadisticas"). The logo in the lower left corner has the initials "TCI" and "EDM" around a small, stylized logo of the western hemisphere and a couple of yellow, right-pointing chevrons.
The seller did say these cards were very rare and he had not seen many of them. I've asked that he let me know if he finds any more as I would be interested. Pity that the other 10 cards had already sold when I finally got around to contacting the seller.
I went ahead and posted the meager 14 cards to SportsCardForum.com's Inventory Manager system, so they are available to the world to search. The highest card number I found was 147, but I would suspect the set contains at least 150. I'll ask the seller if he can remember any more details and post them here.
In other news, I also worked out a deal with the seller of a lot of 2005 Mexican League cards that were produced when the league inked a deal with a new marketing company who updated the league's logo and embarked on a more aggressive advertising and licensing campaign. Apparently that campaign wasn't hugely successful, as this seller has only about 50 cards (though he kept the wrappers, so I'll be getting a couple of those), but there haven't been any further league-wide sets issued. I'll post details on those once they arrive. Again, I probably grossly overpaid, but they aren't easy to find. Once I get them all scanned and cataloged, I'll make them available for trade or sale if anyone is interested.