How to switch between 3G and Wifi for specific applications (both transmitters active) on Android device

I've found this link which leads me to believe it is possible to keep both the 3G and the wifi data transmitters on at the same time.

http://mobisocial.stanford.edu/news/2011/03/let-wifi-and-3g-connection-work-together-by-hacking-connectivityservice-java/

Anyone have any ideas how I could switch between them for different functions? Ie: let sms go through 3G, and video through wifi? I am completely new to this type of low-level coding, so a code sample would be appreciated. 开发者_运维知识库

Cheers