If you've been waiting to get your hands on the Material Design look from the Android L keyboard within the Android L system dump, no doubt you may have already found a way. If you haven't though, a user by the name of bejunk over on XDA has been kind enough to start a thread that gives everything thing you need including instructions on how to install a working version of the keyboard from Android L. There are specific devices listed as to which ones the keyboard has been tested on working seemingly without issue, including the Nexus 4 on Paranoid Android 4.4.4. The keyboard was also tested running on the Xperia L(how appropriate) with PA 4.4.4, and on the Galaxy Nexus on PA 4.4.4 as well. Other confirmed working devices that got the test were the Xperia Arc running CM11, the Galaxy S5 with Phoenix ROM, the Galaxy S4 and Mi3 running on 4.4.4, the LG G2 with Android 4.4.4 stock, the HTC M8, the Galaxy Nexus running a 4.1.2 based ROM, and the Galaxy S3 on CM10.1.
Bejunk further goes on to note that all devices running 4.x.x ROMs should be able to flash the keyboard and have it work, although that is by no means a guarantee as not all devices have been tested. With that said it's best to make sure you do a solid backup before attempting to flash the ZIP files for the keyboard, just in case there is a bug you don't like or it isn't quite compatible. The main process to install this keyboard refers to rooted devices with tests on specific ROMs, but there is a link at the source to install an apk for non rooted devices.
If you're not rooted, head to the link below, then on the XDA thread scroll to find the download link for "non-root users", and it will take you to the thread with the intsructions and link for the Android L keyboard modded apk. For everyone else, your download links can be found from the link below at the original thread. First make sure you do a backup using TWRP or ClockworkMod recovery, then download the file from the selected link.(there are a few to pick from, but when I personally tried the Dropbox link i got an error due to the link owners heavy traffic)Before you do anything else, you have to uninstall Google Keyboard(bejunk mentions this doesn't work for non-rooted Nexus devices because Google Keyboard is a system app and can't be uninstalled), after you have done that you can flash the Android L keyboard zip file via your recovery of choice. Once you have the keyboard installed, getting the material design is as easy as going into keyboard settings, then to advanced/expert settings, and choosing Material Design from the color scheme. That's it. Enjoy Android L keyboard and if you're flashing this on a device that isn't listed as tested, please share your results via the original thread for this download.