Seems to me as though this should be fairly easy to implement in Hijack?

Not that I can see - AFAIK, hijack's visibility is limited to the playing mp3. The only way that I could see to get the next track info into hijack would be to screen scrape the Now&Next screen anyway, which would be rather self-defeating.
However, that being said, if I am wrong and that information is available then the easiest way to implement the info screen that you want is going to be via emphatics custom info mode.
Otherwise I think that you're out of luck - I can't honestly see the demand for this being enough to prioritise it in the next release. But then again, the empeg team sometimes surprise us all