Read the rest of the hint for the script...
#!/bin/sh
if [ `whoami` != "root" ]; then
echo "You must be root to use this!"
exit 1
fi
TGT="$1"
if [ "$TGT" = "" ]; then
echo "Usage: $0 target_volume"
exit 2
fi
logger -t backup "Backup started"
date
asr -source / -target "$TGT" -erase -verbose
vsdbutil -a "$TGT"
rm -rf "$TGT"/var/db/volinfo.database
rm -rf "$TGT"/var/db/BootCache.playlist
rm -rf "$TGT"/var/db/NetworkInterfaces.xml
rm -rf "$TGT"/var/db/PowerManagement.xml
rm -rf "$TGT"/var/db/SystemConfiguration/com.apple.PowerManagement.xml
rm -rf "$TGT"/var/vm/swapfile*
rm -rf "$TGT"/Library/Preferences/SystemConfiguration/NetworkInterfaces.plist
rm -rf "$TGT"/Library/Caches/*
rm -rf "$TGT"/System/Library/Caches/*
rm -rf "$TGT"/System/Library/Extensions.kextcache
rm -rf "$TGT"/System/Library/Extensions.mkext
rm -rf "$TGT"/TheVolumeSettingsFolder
rm -rf "$TGT"/Users/ataraxia/Library/Caches/*
logger -t backup "Backup completed"
date
[robg adds: You'll need to make this executable with chmod 755 scriptname, and as noted, it must be run as root via sudo. I have not tested this script!]

