Alright, using the XDA guide already linked, I did steps 1-6 as written (step 1 has a link to the files you need).
Then, instead of mounting the phone through Clockwork Mod, I restarted the phone. Then, from the home screen, I pulled down the notifications bar, clicked on "USB connected," and then used that to mount the phone onto my computer desktop. I took the file "su-2.3.6.1-ef-signed.zip" from the adb folder that you download in step one and copied it to the mounted phone icon on the desktop.
I then repeated steps 2, 4, and 6, which took me back to the bootloader and reloaded Clockwork Mod (this is necessary since restarting the phone at the point I did wipes Clockwork Mod).
At this point, once you repeat step 6, you're back in Clockwork Mod, and have the necessary file on your phone. You can then do step 17 and the second set of instructions in the XDA guide. It sounds confusing but it's actually very simple. It's also helpful to look at the code for each step and see what it's doing. That way, if you mess up, you can see where you might have gone wrong.
Did that help?