GTA IV (steam version) ScriptHook .net Script. Drop it to "scripts" folder in game install folder. Press M to quick switch to IndependanceFM.

radio-switcher.cs

using System;
using System.Windows.Forms;
using GTA;
using GTA.@base;


public class InvincibilityScript: Script {

    public InvincibilityScript() {
        BindKey(Keys.M, new KeyPressDelegate(ToggleInvincibility));
    }

    private void ToggleInvincibility() {
		// new IndependanceFM index is 21. But ScriptHook uses an old value 18.
		//Game.RadioStation = RadioStation.IndependanceFM;
		Game.RadioStation = (RadioStation)21;
		Game.DisplayText("Switched to IndependenceFM");
	}
}