Hiding Apps

I want to do the thing where you double-tap the app's spot and it unhides it. I found a how-to online for this, but it didn't work. How is this done? I am NOT talking about poof. I already know about this, and I use it for other things (Safari, for example, because I use opera). Please help me with this. I am running 4.2.1 on an iPod touch 2nd gen non-mc model. http://www.iphonealley.com/news/instantly-hide-unhide-iphone-applications This is how I tried to do it. I HAVE rebooted after doing this.

 

Yes, I have jailbroken. I didn't find the file in the specified location, but I created it, and found the same file in 2 other places, so I edited those too. It still doesn't work

 

True, it did say "This feature made it into the newest OS" (probably 1.1 or something at the time). That hadn't occurred to me.