Don't call me wrong, because I stated a clear answer to your question. Like alot of people before you tried.
It is quite obvious that it won't work. since you are only allowed to stay in your sandbox, and you are not allowed to be snooping around in the iphone around the app (if you would have read the documentation/and or google).
The only things that are allowed outside your app, is like, checking for WIFI/Camera and setting the settings, but even then, it's controlled by the OS.
So like Robbie(Duncan) said.
There is probably a way in this "engine" that it will remember on your device, on a webservice or something, what apps you have installed or de-installed.
And in every app it can load this. it's a dirty trick, but hey, it should work.