This awesome tweak can do all the jobs mentioned above, and that means you can substitute SBSettings with your voice command.
VoiceUtils is categorized as a Mobile Substrate tweak which won't add icon to your homescreen thus no settings exsist, once it's installed it will up and running. And supports all device with Siri installed, for non A5 device like iPhone 4 can uses it too as long it has Siri ported using Spire tweak.
You can download VoiceUtils from the Big Boss Cydia repository. If you haven't jailbroken your iPhone 4S yet, you can find instructions here.
Sure it is a free tweak, that is available under BigBoss repository once you launched Cydia and find VoiceUtils package.
But above all, your device must already been jailbreak, if you have not then follow this tutorial to untether jailbreak your iPhone 4s. Or if you are using iPhone older than 4s and own Siri Proxy, you can jailbreak it untethered using Corona.
Now your iPhone 4s understands more voice commands that are currently absent to it previously. Therefore go ahead and reboot your iPhone 4s through your voice!