First I had 2 Windoze installations. The ntldr worked fine. It was installed in the MBR. My challenge was to invoke the GRUB using ntldr. A rather simple task after I accomplished it! Just copy the first 512 bytes of the linux partition into a file, and then reference this file in boot.ini (the bible and the koran and what not, of the ntldr). It now thinks this reference is a windoze installation itself, when it reads the entry in the file. But the "file" is actually the loader for the GRUB. Now the big question is how to get hold of the first 512 bytes. Simple. use 'dd' command! It's too simple to use.
Messed up bootloader? Simple. First decide which one to be placed on the MBR. If it's GRUB, then simply run grub-install with the partition/ide- specific device identifier. eg. grub-install '(hd0)' installs grub onto the MBR. hd0 is the first HD, on the primary IDE. Suppose i need to restore ntldr to MBR. Simple. Run a recovery console from an XP installation disc and use the FIXMBR command. it "fixes" the windoze.
Cool, right? But very risky too. One wrong move, and your entire HDD will be wiped clean!