You can use IPA Installer (BigBoss) and AppSync for IOS 5.X -> 9.X (HackYouriPhone) to install IPAs on iOS 5.X to 9.X. This method is all on-device and is a lot easier than any of the above mentions.
Quick sidenote, can we have an iOS version that's built for 16:9 displays? I'm not happy with...