How to reset OS X 10.6 to "Factory Fresh"
It's a bit late, but I hope this helps someone. Just did it myself:
Here are the Terminal commands to delete a temporary (or lone) account in single-user mode on Leopard (in the following commands, replace username with whatever account short name you've created). Note that this must all be done in single user mode (hold Command-S during boot).
How to Reset your Snow Leopard 10.6 Mac to "factory fresh" user experience with setup assistant:
Note: this does not securely delete data. If you are transferring this computer to another person, do a secure wipe, reinstall, run your updates, and THEN do this to clean up after yourself and provide a new experience to the recipient.
-Make sure your temp account has a password set, however short.
-Boot to single user mode by holding down Command+S when powering on until you see the boot sequence start.
-Run these commands (the $ means the prompt)
Code:
$ mount -uw /
$ rm -R /Library/Preferences/
$ rm -R /Users/USERNAME/
$ /bin/launchctl load /System/Library/LaunchDaemons/com.apple.DirectoryServices.plist
$ dscl . -delete /Groups/admin GroupMembership <username>
note: this line doesn't seem to be needed: $ dscl . -delete /Users/USERNAME
$ rm /var/db/.AppleSetupDone
$ shutdown -h now
that's it.
If you want to boot up and verify, let it boot, set your volume level and when you get to the first setup window press Command+Q to shut down without leaving any traces.