That is a very difficult site to navigate.
That ROM file needs to be on a boot floppy plus it probably needs either a Flash Utility or a command line instruction.
The closest I can find from their site is that the flash utility might be available on a Recovery CD that should have come with the computer.
Sorry I cannot be more specific.
Most motherboard manufacturers bundle their BIOS with the necessary installer.
And just as I forgot to mention: If your BIOS Error was a Check Sum Error then this further implicates some hardware issue. You might want to test just removing the connection to the CD drive and see what happens or doesn't.
As to the BIOS: do you have a motherboard CD from Mercury?
Another angle would be to trace the make and model of the computer.