Although ASUS issued a strong warning against users unlocking the bootloader on their Transformer Prime, they just made it available for download. They also made it plainly clear that if you do so, and accidentally wreak havoc on your device, then they will not support you. Still, for the tinkerers among us, this is a cool thing coming from the manufacturer. Here is ASUS' statement on the issue,

You also acknowledge ASUS does not guarantee service satisfaction to any Revised Product, including events involving paid service requested by you to be performed to the Revised Product.

Furthermore, such repaired Revised Product will not be covered under the warranty of the Original Product; the software of the repaired Revised Product will not be deemed the software of the Original Product and will not receive ASUS software updates.

It is strongly advised that you avoid activating this App unless you fully understand and accept the risks that may arise.
Now, if you still want to proceed, feel free to head to the download link below on Asus' Support site. Also, don't forget to ask in the forums for assistance if you haven't done it before. Be very careful as you could potentially brick your device, and we don't want that!

Source: TransformerForums via Asus Support