Installing iPhone/iPad application ad-hoc

At my current job, I had to remotely install some beta versions of the iPad app for some clients, before the app was actually released on iTunes. There are several steps that one has to take in order to achieve that (assuming you have followed some of them that describe creating Certificates, App IDs, etc):

1. In your iPhone Developer account, go to the iPhone Provisioning Portal, the to Devices, and add the iPad device to the Current Registered Devices section. You have to know the Device UDID (40 characters that can be copied form iTunes when you have the iPad plugged into your computer).
2. Add the newly created device to the Distribution Provisioning Profile. 
3. On you station, drag-and-drop the distributed provisioning profile into XCode. 
4. Under XCode, change both your app's and your target's build properties to use the new distribution provisioning profile. 
5. Delete the old Entitlements.plist file and create a new one.
6. Change your settings so that XCode uses Device as the Active SDK, and Distribution as the Active Configuration. 
7. Build your app, then zip the executable. 
8. Export your private key and the developer identity certificate and import them into your client's Keychain (you might also need to export-import the AppleWWDRCA.cer file to your client). Finally, add the iPhone distribution certificate to the Keychain. 
9. Download the new distributed provisioning profile and drag-and-drop it into your customer's iTunes app (either drop it on the iTunes icon, or in the App section). 
10. Un-zip your application and drag-and-drop it into the app section of your customer iTunes (if the Apps section is not visible, go into iTunes -> Preferences and click on the checkbox marked as Apps). 
11. Synchronize iTunes with the iPad to transfer the app from iTunes to your client's iPad. 

Hope it's going to help some of you. Enjoy!