Multiple fallbacks from Cdrom

[adrian15]

I am interested in using multiple fallbacks as described in:
http://www.gnu.org/software/grub/manual/grub.html#Booting-fallback-systems
however I'm not sure if I can use this option from a cdrom or floppy 
because I do not know if I need to be able to write a file, that I think it 
was savedefault or default or somethin on /boot/grub.

The question would be:

          default saved
          timeout 10
          
          title GNU/Linux
          root (hd0,0)
          kernel /boot/vmlinuz root=/dev/sda1 vga=ext
          initrd /boot/initrd
          savedefault
          
          title FreeBSD
          root (hd0,a)
          kernel /boot/loader
          savedefault


This menu.lst would work correctly from a grub cdrom?

Thank you.

adrian15