[intrlude]

I believe that AdvancedConfig gives you an option. Open AdvancedConfig press Menu followed by More settings > click Connections. You should see Phone as Modem and your "data" connection (depending on ROM is the name). Click til shows disabled.

Tested by disabling and trying the weather app. Gave me an error "couldn't connect". Connected WiFi and was able to update weather.

And incase you don't have it, here's the cab file.