I did some searching over at the XDA forums and heard that the wallpapers with Vire Launcher work.
All you are left with is a black background of eternal nothingness-and that’s about the most unimaginative, un-customized thing you can get.
VIRE LAUNCHER KINDLE FIRE HDX INSTALL
The launchers install and work, and unlike previous Kindle Fires you can set them as the default so pressing the home button bypasses the Kindle homescreen entirely. I’ve tried installing a half dozen different launchers-Nova, Apex, ADW, Go Launcher EX, etc-and it’s the same story over and over again. The only problem with alternate launchers is that Amazon made it so wallpapers no longer work on the Kindle Fire HD after a software update, and unfortunately it’s the same story with the Kindle Fire HDX. Alternate launchers can give the Kindle Fire tablets more of a true Android tablet look-and-feel. Installing an alternate launcher is one way to avoid having to use Amazon’s homescreen. Everything’s all just thrown into one big carousel of images whether you want it or not. You can’t even control what types of content appears on the homescreen.
In fact the Kindle Fire HDX and earlier models are the only tablets I can think of currently on the market that offer no user-customizable options at all. From a software standpoint, every Kindle Fire on the planet has the exact same look-and-feel, the same exact homescreen, the same exact carousel and favorite’s menu setup.