You cannot simply extract it. This still has root since it is a test release. I recommend just doing an adb pull of your system directory after you flash it. Don't do this when the final one comes out or else you might be stuck without root.
You will need to add busybox, patch sh and su, and make sure that you do another recovery image and such. I also recommend adding Superuser.apk and stuff. If you use the Desire build.prop, you can get most of the protected apps working.
Leak, I know who you are.