I started to port Tizen on Nexus 7.
To install it, you will need an unlocked Nexus 7 and MultiROMv7. MultiROMv7 is a way to have multi boot on Nexus 7. Once Recovery and MultiROMv7 are installed, you must reboot into recovery. Send image on your Nexus 7:
adb push /path/to/image/Nexus_7_Tizen.zip /sdcard/
After click on install button and select Nexus_7_Tizen.zip. It will install Tizen on your Nexus 7. Now you can reboot. In list of ROM, you will see Tizen_Testing. Select it and enjoy.
Tizen ROM: http://easymt.org/files/Nexus_7_Tizen.zip
In days, I will publish instruction to build the ROM.