Wasn't the Surf Squirrel capable of booting off a CD? This may only have applied to CD32 games though.
CD-ROM drives don't appear in the Early Startup Menu so it would be interesting to find out at what point they are recognised by the system. It might be possible to put one of those boot selectors in your User-Startup and have it execute an S/Startup-Sequence on the CD-ROM. Might work...