boot from usb hd

[David Bauer]

Hello,

how can I boot FreeBSD from an external USB drive if the BIOS does not 
support this ?
I could install 5.2 on the USB disk without problems. The only minor 
problem was that the system did not reboot correctly after finishing 
installation. But if I boot from live CD then I can mount the slices from 
the USB drive and all seems to be OK.
So the only remaining problem is: How to boot this.
Is it possible to boot some kind of mini kernel from floppy, which makes 
the USB drive visible and than boot the FreeBSD kernel from the USB drive ?
I experimented a bit but so far without success.
So any hints are wellcome :-)

Thanks so lot,
David.