Here is a walk through guide on how to add .ipa apps to your iPhone or iPod Touch after successfully jail breaking it. Several have left that part out. Please be sure to BACK UP your mobileinstallation.framework file that you will be modifying in the guide below before you modify it.
REMEMBER: You can not brick your iphone/ipod Touch. You can always do a recover or even a full apple restore which takes it back to before you jailbroke it. No worries. If you get froze in the pinapple screen be patient it takes time to load all your cool apps. If however it remains frozen at the pinapple after a few reboot ( holding power/home)attempts , reconnect to your SFTP ( Cyber Duck) and check your mobileinstallation.framework file. Be sure that you follow the guide bellow and have the 775 perms set as instructed. This can freeze things up if not. You can always replace the entire file with your back up if you made a mistake and can not get past it. You just replace that whole file and start that part over. Remember to reboot after.
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"Open your SSH client on your computer, and SSH to your iPod Touch/iPhone (as shown here)
In CyberDuck (or whatever application you’re using for SSH), browse to ‘/System/Library/PrivateFrameworks/MobileInstallation.framework’
SSH to this folder.
In this folder, there is a file called ‘MobileInstallation’. If you want, you can back up this file, and it’s probably a good idea to do so, in case anything goes wrong (which almost definitely won’t, but you never know…)
After backing it up, replace this file with the MobileInstallation file you downloaded. Once you have done that, you need to change the permissions of the file.
In CyberDuck, this is done by right-clicking on the file, and going to ‘Info’. In most programs it will be similar, if not the same.
Right Click on the MobileInstallation file, and go to 'Info'
The ‘Info’ page will open, giving you the option to change the name of the file, and the permissions. Change the permissions to 775, like below:
Change the permissions to 775."