What I would do is push psneuter to /data/local, chmod 777 to psneuter, then run psneuter. Now when you run adb shell you should have root. Now remount /system with read write permissions, push su to system/xbin then chown 0:0 to it and chmod 6777 it, now you should have su ready. Restart your phone and now you should have superuser and try running rom manager now. I had to do this to get superuser to run correctly, basically what your doing is getting su to work correctly with your system because for some reason clockwork mod is not accessing superuser correctly. Without gaining superuser permissions you will not get recovery to flash correctly.