Hi Alex,
I am just bidding on this project , to let u know that this project is not possible in current framework of android.
If someone is saying he can do it , that is a false statement.
What i can provide u is an application which once started will stop user from doing anyother operation. he wont be able to switch applications , he wont be able to sms or call anyone neither he will be able to recieve or pick any call or sms. even on restarting the devcie the application will not quit. The only way to quit will be through a password.
Let me know if interested.