Only the AxpPCI33 is known to include failsafe boot block floppy support (Section E.5.6 Noname).
If you do not have a standard pre-built Milo .dd image, then you may need to build an SRM boot block floppy. Once you have built Milo, you need to do the following on Digital Unix box:
fddisk -fmt /dev/rfd0a cat mboot bootm > /dev/rfd0a disklabel -rw rfd0a 'rx23' mboot bootm
Or on a Linux box:
cat mboot bootm > /dev/fd0
If you have a standard Milo image available (say milo.dd) then you would build a boot block floppy using the following command:
dd if=milo.dd of=/dev/fd0