Windows wipe my MBR. I can't start grub

[nickel]

hi!
i tried to install windows 98 using the cdrom of windows xp. I don't have a floppy drive. I formated one partition with windows xp, but i couldn't install windows98. That was quite stupid. Windows wipe out my MBR and i can't use grub. I installed gentoo following the instructions they gave for the install. So my partition table looks something like this:
/dev/hda1 /boot 31 Mb
/dev/hda2 swap 512 Mb
/dev/hda3 / 10Gb
/dev/hda4 fat32 2Gb
Please, can someone help me?

[stormrider]

Fire up your live gentoo cd and do the following.

mkdir /mnt/hda3
mount /dev/hda3 /mnt/hda3
chroot /mnt/hda3
mount /dev/hda1 /boot

Then follow these directions.