This video tutorial from iWalous shows how to install Bossprefs on your jailbroken iPhone from Cydia.
Boss prefs utility allows to easily configure such iPhone functions as 3G, EDGE, WiFi, Bluetooth, and SSH.
From main menu click Cydia. Install any updates or upgrades if there are any. Click Research button. Type in bossprefs in search area.
Scroll down search results and tap the link that says BossPrefs.
Double click Modify button. The aplication will be installed. Restart it so it can be operated properly. Now you will be able to easily activate and deactivate such services as 3G, Edge, Wifi etc.