We are working to create an official 1080P Firmware for the MK802IV...
It shouldn't be long but if you cant wait (I know theres some digital signage guys out there that need this) heres a solution courtesy of NEOMODE over at Freaktab.

http://www.rikomagic.co.uk/downloads/Freaktab_MK802IV_1080p_ROM.zip
This is based on 4.2.2, Rooted and good to go...
For more info you can check out the post http://www.freaktab.com/showthread.php?5404-NEOTV-CROM-for-Flycast-MK809III-UG007B-QC802-Cloudnet-Go-CR9