This is what I am thinking. If this works, this could be the perfect solution.
A USB DVD-ROM drive.
No more having to remove the internal DVD to wire up another one. Just plug up a USB DVD drive to a controller port.
You could add an option to the EvoX menu to get it to boot from this DVD drive. And in future I'm sure a BIOS patch could be added to get the box to try and boot from this drive, and then the internal drive, without too much difficulty.
Sure, it wouldn't be as fast as IDE. But it's still like 1.25MB/SEC, which seems to be about as fast as the internal drive reads original Xbox games anyway. So all in all, pretty good solution if you ask me.