It's a proof of concept, the main CWM Recovery comes from Samsung Galaxy Tab 3 (P5210), credit to Clockworkmod Team and the team made the P5210 porting.
This is the original environment I'm using to pack recovery.tar:
cd ramdisk
change something
tar zcvflp ../update/system/bin/recovery.tar .
and use install.bat to install on the phone. For packing update.zip, just zip the update directory.
Keep eyes on the notification LED on the top of ZenFone, when it turns red during boot, press volume UP or DOWN and wait for seconds.
Not fully tested, use on your own risk.
http://23pin.logdown.com/posts/211564-cwm-recovery-for-zenfone-5-poc (Chinese)