After hackers discovered in January that the bootloader on the ASUS Eee Pad Transformer Prime was locked and encrypted, a huge outrage ensued – and ASUS quickly backed down, promising to develop an officially sanctioned unlock tool. It has now made good on that promise and released the tool to the public
To fully take advantage of an unlocked bootloader, however, you'll need some special software known as a recovery, which can allow you to flash custom ROMs and backup your data, among other things. The most popular custom recovery, by far, is ClockwordMod, and it was promptly ported to the Transformer Prime soon after the unlock tool became.
Before continuing, it should be noted that unlocking your bootloader will void the warranty, permanently. Whereas you can usually revert unlocked and rooted Android devices to their original state, this is apparently not the case with the Transformer Prime – and just to make that point extra sure, ASUS seems to have built in a mechanism in the unlock tool that sends in the serial number of the CPU and subsequently marks its warranty as voided, according to a post on the xda-developers forums.
If you don't care for your warranty, though, here's how to proceed: visit the support site, select the "Utilities" category and download the "Unlock Device App". It literally is an app, and thus can be installed like any other APK. After following the instructions and a reboot, you bootloader should be unlocked – great. Now, just head over to AndroidRoot.mobi to get the files needed for ClockwordMod Recovery.