Yes, it is possible.
grub> setup (hd0)
grub> install (hd0,0)
This will install the grub which is on 1st partition of 1st hardrive to 1st hardrive, overwriting anything that's there (lilo or another grub).
Warning: be careful with that, as you may not be able to boot anymore, if the new grub is not functionnal.
Last edited by Agrouf; 06-05-2008 at 07:43 AM.