The USB to SATA adapters found inside these types of things are much smaller, cheaper, and more readily available. They also have the advantage of being bus-powered and a USB cable is a lot easier to bend into position than a 40-pin IDE ribbon. Of course, adding USB host to an empeg may outweigh the price advantage...[/url]
The original poster intended to add USB host by connecting it to the IDE bus. Unless somebody removes the existing USB chip and finds a way of fitting a USB host in its place, that is the only viable method of doing it internally.

The PATA -> SATA adapter I linked fits onto the back of the drive. If necessary you could remove the soldered on SATA connectors and put a lead on instead. Same with the PATA pin header.

[url=robricc]I remember the turbonet ethernet cards for Series 1 Tivos achieving 22Mbps without DMA. Even if only something like 15Mbps is possible, that's a whole lot better than 10Mbps.