It has to be in the admin/user.php file (your sure you edited the one in your admin folder?) where you screwed up. Check that part of the instructions again very carefully. Pay particular attention to these:
Replace it with:
Add the following directly below it:
Add the following directly above it:
And if it still doesn't work, don't feel bad, because I can't get the new version of this hack to work right on my RC2 board. It works, but it seems to put me into miserable mode too, then lock me out of my own CP!
I'm sure you made a copy of the three files before you edited them, right?