Before you start the process, you need to keep this mind that Installous 5 has been banned by the Apple Inc. and old methods of installing this app to your device are of no use anymore. However, there are still ways that can help you install Installous 5 on iOS 5.1.1.
You need to have a device that is jailbroken. A factory unlocked device won’t allow you to install Installous 5 on it. However, you can jailbreak your device using Redsn0w and then you can proceed to the process of installing Installous 5 on your device.
Once your Idevice is jailbroken, you can launch Cydia from the Springboard. You will find that the jealbreaking process had automatically added Cydia to your device. Launch Cydia and tap the Manage tab. You can find that Tab at the bottom of the screen.
You will see a new screen after tapping the Manage tab. Click on Sources and wait for it to load. It will take half a minute but can take more depending on the speed of your internet.
Now look at the top right corner of the screen and you will see an Edit tab. Tap then button and a new screen will appear. There will be another tab title Add. Tap it and you will be asked for Cydia/APT URL. You need to enter the following address in it. cydia.hackulo.us.
Now tap Add Source to add Hackulo.us repo. At this stage, Cydia will take few seconds to update the necessary database. Do not turn off the device during the loading process. After the completion of the process, simply tap Return to Cydia at the bottom of the screen.
Now back in the main menu, tap Search and type Installous into the search box. You will see different version of Installous but tap on Installous 5 and tap Install at the right top of the screen. This will install Installous 5 on your device. Tap return and reboot the device.