I could get root as the same way as in the 2.3.
ADB shell mount -o remount,rw /system
ADB push su-126.96.36.199-efghi-signed /system/xbin/su
ADB push su-188.8.131.52-efghi-signed /bin/su
ADB shell chown 0.0 /bin/su
ADB shell chmod 04755 /bin/su
ADB shell chown 0.0 /system/xbin/su
ADB shell chmod 04755 /system/xbin/su
ADB shell mount -o remount,ro /system
ADB install -r Superuser-3.0.7-efghi-signed.apk
But I flashed back the 2.3 because there were an incredible battery drain in 4.0. In idle mod the tablet drained as fast as when the screen was on...