OK, Jeremy.... here's the skinny. Through the browser, and programtically, it's impossible to change the browser history. As has been posted before, the history is READ ONLY! There is no available module that will allow the browser, or any script, to alter it's contents. That doesn't mean that one can't be built. Also remember that ActiveX only works with IE browsers - no others. Additionally, on the initial page load, the user will be notified that an ActiveX module is required to be downloaded and installed in order to see the page - and they MUST authorize this, otherwise, no dice.
Now, let's assume that you can get as far as this notification... in light of the viruses being passed around in that last 60 days, it's doubtful that many users will give the OK to download anything that they know nothing about. I know I wouldn't.
Now let's touch on the ethics of changing the users browser history. Quite frankly, you don't have the right to change ANYTHING on ANYBODY's computer without their explicit authorization. PERIOD! The beauty of the internet is that people SHOULD be able to surf as they please and not worry that a malicious web site will destroy information on their machines. Once you cross that line then you have entered the ranks of those who have nothing better to do than to create and spread viruses. And let's not forget the part about ERASING the history file. Shame on you!!!! (If I ever found out that your web site erased my history file, or any other file on my machine, I'd make it my mission in life to sue your pants off!)
I can think of no valid reason to do what you want other than to hide something that you're ashamed to let others see . Again, this concept goes against the reason why the Internet is the single most widely used information medium that the world has ever seen - users expect to be able to "surf" when and where they want without the fear of harm or damage to their machines - and you, as a web page creator/owner/developer, do not have the right, under any circumstances, to do anything more than to attempt to place a cookie on the users machine.
As you can see, I'm not as enthusiatic as you wanted me to be. I won't apologize but I will say that I am sorry that someone as seemingly intelligent as you would continue to persue such an endeavor. Please let me know what your web site address is so that I can be sure to avoid it!
There's always a better way. The fun is trying to find it!