AppSync is an iPhone app that allows you to patch MobileInstallation file on iPhone OS 3.x firmware . Once the MobileInstallation file is patched on iPhone you can easily install .ipa files manually without using iTunes and paying apple. AppSync can be installed via Cydia, so make sure you have jailbroken your iPhone with firmware 3.1.2.
Steps to Install AppSync on iPhone 3.1.2 firmware
Step 1 - Start ‘Cydia’ on your iPhone springboard.
Step 2 - Select ‘Manage’ tab at the bottom of your iPhone screen and then select ‘Sources’.
Step 3 - Select ‘Edit’ and then select ‘Add’. Now enter a url source. Type ‘http://apt.macosmovil.com’ and select on ‘Add Source’. Once Cydia has added the source click on ‘Return to Cydia’ button.
Step 4 – Once the installation is completed. Search for “AppSync para OS 3.1(3.1.2)” in Cydia and install it.
Step 5 – This app will automatically patch MobileInstallation file on your iPhone OS 3.1.2.