To create an IPA from your PhoneGap project, you need to have setup and initialised an Apple Developer Account. You also must have created an AdHoc Certificate and installed it locally.
There are two ways to create an IPA using the PhoneGap CLI:
1) phonegap build and XCode
Run the command:
phonegap build ios
in your PhoneGap project. This will create an XCode project in the platforms/ios/ directory. Open that project in XCode and follow the directions for creating an IPA from XCode.
2) PhoneGap CLI
If you are running the latest version of PhoneGap, you can just run the command:
cordova build ios --device --release
in your project. Assuming you have a Wildcard AdHoc Provisioning Profile installed on your system, this will just generate the IPA in the platforms/ios/build/device/ directory.
Just upload your IPA to Installr and you are ready to go!