im on alltel, not sprint but...
I haven't let my phone run the ext rom customization feature ever. never on my 6700 and never on my 6800. if you ask me its all junk. i really dont think any of its necessary but i could be wrong. if you are a fan of the automation process then u can customize your ext rom.
heres the link to doing that:
http://forum.ppcgeeks.com/showthread.php?t=1258
its for apache but dont see why it wont work. i havent done it with the titan
To make the ext rom NOT install after flash or hard reset then do a soft reset right when the 'customizing will begin in 3...2...1' popup runs.