The image argument to pygrub does not need to be an integer. The "invalid literal for int()" error probably means that your menu.lst contains something like "root=(/dev/sda)". The root should be specified in grub notation like "root=(hd0)".
You might want to have a look at /boot/grub/devices.map. To map /dev/sda to hd0, you could add an entry like: (hd0) /dev/sda -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org