I'm not 100% sure with 10.04, but I think upstart is responsible for starting myth-backend. Have a look in the /etc/init directory for a file names mythbackend.conf.
The prestart script waits 5 seconds before continuing.
# MythTV Backend service
description "MythTV Backend"
author "Mario Limonciello <firstname.lastname@example.org>"
start on (local-filesystems and net-device-up IFACE=lo and started udev-finish)
stop on starting shutdown
exec /bin/su -c "/usr/bin/mythbackend --noupnp --logfile /var/log/mythtv/mythbackend.log --user mythtv -v eit" mythtv
If your system doesn't use upstart then the script will be in /etc/init.d and be called something like mythbackend.