The popular 3rd party CyanogenMod CM10.1 has been launched for the older Xiaomi M1, M1s and M1 youth phones.
Xiaomi release updates and bug fixes to their phones on a weekly basis, and although the current version of MIUI V5 boasts most features found in Android 4.2, it is actually based on Android 4.1.1. This isn’t likely to change either as Xiaomi have stated their efforts will go in to the next Android release.
However if you happen to be the owner of the original Xiaomi M1 or the updated M1s and M1 Youth you can get Android 4.2.2 on your phone right now with the release of CyanongenMod CM10.1.
The ROM isn’t without it’s issues though as tethering is not available. If you do want to give it a go though you can download it from here.