Don't mind me, just bumping an old idea.
I'm not sure how to do it with the MTG Preview Generator, because the link names are all constructed with a SETNAME + CARDNAME query. I'm sure it could be done, it'd just be a lot bigger pain in the butt.
That said, if you were to use the simple JPEG addresses it would probably be a lot easier to pull off.
Let's say you set a [CARD] tag, it can pull from this link:
http://www.wizards.com/global/images/magic/general/CARDNAME.jpg
It appears that spaces, hyphens, and special characters would need to be replaced with underscores for the name to work properly, but that "general" directory does appear to contain every card ever printed.
Maybe you click on the CARD tag and it brings up a prompt box similar to the URL tag? But instead of having a link & name box it just consists of a name box.
I have no idea whether or not this would be legal without WotC's consent.