I want to install an AdHoc IPA file to an iPhone, but I don’t want to back up the apps of iPhone into iTunes, because the iPhone is not mine, and there are too many apps in it. Is that possible?
You could also use Xcode (at least Xcode 4, haven’t tried it with earlier versions):
Open the Organizer and select ‘Applications’ under your device in the Devices tab. Now use the Add button to add your ipa to the device.
This web app may be what you need: http://testflightapp.com/
Take a look at Hockey, from the project description:
Hockey is a iOS Ad-Hoc updater framework. It can be used for all apps that target the Apple AppStore and improves the beta testing process dramatically. All beta testers. It consists of two components, a server and a client framework.
The server component is required for all scenarios. But it also can work standalone without the client library. It provides a web interface which beta testers can use to install the latest AdHoc provisioning profile and also the latest beta version via Safari right from the device. One server installation is able to handle multiple applications via different bundle identifiers
This procedure was published this morning, so I am not sure if it works as advertised. Basically it talks you through setting up Adhoc distribution OTA in something like ten easy steps.