Whoa! Crazy idea, like! DirectX 9 registry-tweaks!Bells and whistles, ho!
*I'll be back.*
[Later]
Hm... Dude, I only dug up some Speech-API-entries. Well, ONE, actually...
DWORD: SpeechIngame, set to 1. Same location as the other two. I haven't tested it myself yet, so don't shoot me if it doesn't work.