The only distro that I've found that needs the cromwell bios is xebian, and then only if you want a 100% pure linux box. All the other distro's appear to be loopback installs (xebian has this option too).
Sorry I can't be of more help, I've only just learnt this myself, as i was hoping to do a native install of xUbuntu and couldn't work out why it wouldn't work.
Edit:
This is what i was following, until i hit the problem of having to find a 2.6 kernel
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