Back on topic, I don't think we'll be able to find an off the shelf part small enough. I've had a bit of a look and most SATA-IDE converters are for 3.5" drives. The separate power connector of 3.5" drives further makes the conversion more bulky.

i.e. something like http://www.addonics.com/products/io/adsaide.asp

Really it's going to have to be a custom design I think. There are single chip solutions, so someone could design a suitable PCB from scratch. I think it would be physically possible. Obviously there would be quite a limited market for something like this so unless someone here does it, it's unlikely to happen. Although I have no need at all for the large drives right now, this sort of thing does interest me and I might invstigate a bit further.

It's certainly ballpark feasible in my opinion but space could be an issue.