1. Create a Distribution Ad-Hoc Provisioning Profile in the iOS Provisioning Portal. Download the profile and install it onto the computer that builds the app.
2. In the project Build Settings, change the Code Signing Identity to the Ad-Hoc profile.
3. In the Product menu, click Build For -> Archiving.
4. In the Product menu, click Archive.
6. In the Window menu, open the Organizer.
7. In the Organizer, click the Archives tab. You should be able to find the new archive.
8. Click Distribute...
9. Choose "Save for Enterprise or Ad-Hoc Deployment" and click Next.
10. Choose the same Ad-Hoc profile.
11. Choose a name and folder for your app binary. It will be saved in the .ipa format.
To test your app binary, you can give the profile (.mobileprovision) and the app binary (.ipa) to your beta tester. Make sure that when you create the profile, their device IDs are also included in the profile. Then, they will need to drag the profile and the app binary into iTunes->Apps page. When the testers syncs the iOS device, the app should appear on the device.