I haven't found a backup of those files, though some (not this one) are available through archive.org.
There isn't quite enough information - we need the checksum offset value for the 5005xs. If anyone has an official firmware for the 5005xs, that would probably be enough. Otherwise it would probably take a lot of trials to guess at it (creating a firmware CD each time and seeing if it worked).
I have two 5005xs's myself - one to sell after I replace the drive and hopefully find this firmware too.