Note: There is not yet a jailbreak solution for the new (2012) AppleTV 3rd generation. Until there is, Rowmote can not be used with it. The below instructions are for the (2011) AppleTV 2nd generation.
Rowmote is the only app which will control both the standard Apple menus as well as third party applications such as XBMC on your Apple TV. Rowmote Pro's keyboard is fully supported. Please look at the instructions below before purchasing to ensure you're comfortable with the requirements!
Installation requires jailbreaking your Apple TV. This process is not supported by Apple. While these instructions have worked well for me and for many others, I can not guarantee they will work for you. If for some reason the installation fails, you can always 'factory restore' your Apple TV.
Jailbreaking requires a Micro USB cable, which does not come with the Apple TV, in order to connect the Apple TV to your computer for the initial installation. I recommend this cable on Amazon.com as it's just $1.36 plus shipping (free shipping with Super Saver Shipping or Amazon Prime).
If you have not yet jailbroken your Apple TV, see the Jailbreak and Installation Instructions.
If your Apple TV is jailbroken follow the Quick Installation Instructions.