If you’re not comfortable with linux comand lines and have basic knowledge to do recovery from bricks, then we strongly don’t recommend you meddling with the nas WD’s core.
But if you insist, look for the thread by Fox_exe. Hes got the repository for v4 firmwares which means you don’t have to downgrade to install MySQL. phpMyAdmin is quite easy to install but requires extra module php5-mysql.
