There's a registry entry somewhere for something like "delayed ring tone on incoming call". It's on one of the Diamond Tweak programs. I can't remember which one it is but I'll look through my phone and find it for you tonight, can't do it right now at work..
EDIT: Found it, the app is called Diamond Tweak (
http://forum.xda-developers.com/showthread.php?t=409540). It's item 1.7 in the list of tweaks. In case I'm not allowed to post links to other boards, I apologize in advance.