You are doing something wrong. The command
sudo fdisk -e /dev/rdisk0
should bring you to the fdisk prompt where entering the command
should list your partition table. It is short for "print" so try typing that if just "p" doesn't work for some reason (works here on 10.6.2). Likewise, entering the command
flags partition 2 as bootable. It is short for "flag 2" so try that if just "f 2" doesn't work. Make sure to replace "2" with the appropriate number for your HFS+ partition (as identified with the print command).
If you still can't figure it out, type "help" at the fdisk prompt.