Basically, a script to programatically read/write web pages is just a custom browser. The whole idea of the www client/server model is that any kind of browser can be used and the server doesn't know beans, except what the client tells it. As such, what you say is impossible.

That being said, there is a number of loopholes that you can use. merlyn (of course), for example, has an article that shows how to make life hard for robot scripts proporting to be real-life browsing people by showing a picture of a random number or word and making the browser person type in what they see. There are other ways to make it hard but not impossible for scripts to pretend to be people browsing. LOL

drinkd