Can I use any third party tool to flash an Apple device without connecting to iTunes? I want to jailbreak my phone or change the OS. Will this work?
There are a few methods out there, but I wouldn't recommend any of them. The risk would be too high, in my opinion.
For more information: http://www.techyv.com/questions/can-i-flash-apple-device-without-itunes
perhaps over the net but this is difficult and no one will take responsibility if something goes wrong, best to seek the help of experts, there are dedicated forums over the but nothing is 100% since depends also on the state of your iphone hardware. Once going on this direction no coming back to Apple.
Really not enough info for a really definite or specific answer. But it really depends on what version of iOS is on the iDevice. If it iOS 3, then most likely you can jailbreak it with nothing else but the phone via the jailbreak.me website. I would check that out, there website has useful info and is easy to use if your device is supported. With Jailbreak.me 2.0, you just visited the site on the iDevice and slide the bar to jailbreak. I can not imagine it has changed to much, but it does not work on all iDevices, as I mentioned earlier in the post it depends on the version of iOS.
How to check iOS version:
1) Click the settings icon on your device.
2) Scroll down and select General.
3) Scroll down and you will see "Version". This is your iOS version.
All of those are not officially supported. Whichever you do there is no guarantee it will work and you might lose the warranty.
In theory you don't need iTunes to flash your iOS device unless you are using Windows. In that case iTunes has to be installed otherwise the device won't be properly detected.
Since I don't support jailbreaking I can only refer you to the Wiki article with recent informations.
As for changing the operating system I think you are out of luck. I'm not aware of any working alternative.
Android was once ported and hacked to work on the original iPhone and iPhone 3G but I think this project was abandoned sometime in 2010.