An XDA member Cloudyfa has made an app called AutoRec KitKat Recovery Installer, which makes it easy to install TWRP recovery on the LG G2. The tool supports all LG G2 variants and is quite simple use; however, your device must be rooted. Installation guide: First root your LG G2 running on Android 4.4.2 KitKat (you can use ioroot25 for this). Once it is done, install the AutoRec app on the device and grant root permission. Once installation completed, open the app and click on Flash Recovery option. That’s it! The TWRP recovery will be installed. Important: Please note that, the AutoRec KitKat Recovery Installer downgrades your device’s KitKat bootloader and flash a custom recovery (here TWRP 2.7). Therefore, it is a risky job, so install the app at your own risk. Download: This tool is available for all the variants. You can download the app from here. Make user to download the correct app for your device. (source)