- Plug your device into iTunes, allow it to sync fully (thereby performing a backup that you can restore to if anything goes wrong)
- Download iPhone Configuration Utility from here:
http://www.apple.com/support/iphone/enterprise/
- Run the iPhone Configuration Utility
- Drag ****_Ad_Hoc.mobileprovision into iPhone Configuration Utility
- Drag ****.app (found inside the zip file) into iPhone Configuration Utility
- Connect your device, it will appear in the left hand column, at the bottom. Click it.
- There should now be 5 tabs across the top of the screen, click the one called 'Provisioning Profiles'
- Click the 'install' button next to the profile called '**** Ad Hoc' (this is likely to be the only provisioning profile available anyway).
- Click the tab called 'applications'
- Locate the app in the list and click the 'install' option.
- Job done!
(to uninstall, you basically do what you've just done, but in reverse!)