I have installed FreeBSD 8.2 amd64 in my PC for testing.
If you want to boot FreeBSD using GRUB, simply edit
/etc/grub.d/40_customized
In the other section add the following line:
(change the partition according to yours)
menuentry ‘FreeBSD 8.2 amd64’ {
set root='(hd0,X)’
chainloader +1
}
Update the grub.cfg
#update-grub
FreeBSD should appear in your grub menu while booting…