Replacing VoiceOver sounds?

Hello everyone, I'm quite new here, though I've been a lurker here at Applevis for the past two years now. Anyways, I was hoping someone might have an answer to this question. I recently Jailbroke my IPhone in hopes of changing the sounds it plays for everything. Now, the lock and unlock sounds, keyboard clicks, and other system sounds in general were no problem to find and subsequently replace. However, I can't seem to be able to get to VoiceOver's sounds, which are what I'm really hoping to replace. I know it's been done, but I haven't been able to find out how. So, does anyone know how I can get to those elusive sounds? I have a whole bunch of Star Trek sound effects that are just begging to be used...