Android 4.4 builds have been ported to the Nexus devices and as promised, an update will be available for the international version of HTC One within 90 days since Nexus 5 was launched. However, an AOSP (Android Open Source Project) build of Android 4.4 KitKat is now available for the HTC One and has been developed by Stephen Bird.
The AOSP Android 4.4 build for the GSM HTC One is fully working except that IR sensor does not work. The ROM uses the binaries from Android 4.3 update for One.
To get the IR sensor working we need to wait for HTC to release the Android 4.4 update for the Google Play Edition of the HTC One. The ROM has been developed for the International variant. the T-Mobile version and AT&T variants while Sprint and Verizon should get it pretty soon.
Before you flash the ROM, make sure your device has the latest CWM or TWRP Recovery. You can get the latest CWM using the ROM Manager app. Before you flash, make sure you backup all data on your device using our data backup guide or using OBackup. Once the ROM boots, you can use Nandroid Manager to restore apps+data, calls, text messages and Android ID.