http://forum.ppcgeeks.com/search.php?searchid=5468283
check out the one by henbone11
**edit**
as far as not seeing the option in advanced config, i think it is rom specific. i flashed to the new mighty rom the other day and it was not an option, but it is an option for the OEM sprint rom. so you will have to figure out which file is playing at startup and paste over it.