Luckily, the developers and people familiar with this procedure can download the software manually using a channel intended for developers offered by Apple. iOS beta 4 is available for owners of iPhone 3GS, both variants of iPhone 4, all versions of the iPad and iPod touch generation of the third and fourth.
For a successful synchronization, you need iTunes 10.5 Beta 4, also available in the new channel for developers at Apple, along with a new Xcode 4.2 Developer Preview 4. With iTunes WiFi synchronization is supported on PCs with Windows. Note however that in order to upgrade the iOS you need 5 beta 3 is already installed and then switching to iOS 5 beta 4.