My iPhone 3G is giving me some trouble lately. The home button is not working due to some reasons, it only works when pressed hard. Thus, to solve this problem without trying to repair the home button you need to download Activator from your jailbroken device through Cydia. It is available for free download via Big Boss Repository.
After you've installed Activator you can apply certain gestures, motions to specify your required command. For Example: I am using Double-Tap on Status Bar for Switching Between Apps.
Here's the example, to Activate Switcher when you double tap on the status bar.
Peace !
