As you can see by ball's code, there is actually a shortcut in the website for people who want quick hiscore access in a program.

And that is to use the URL "http://hiscore.runescape.com/index_lite.ws?player=USERNAME" which will return a blank page with just the raw data. It works faster and is easier to parse.

I would suggest against making such a program though unless it was simply for experience because it has been done so many times and in so many different ways I'm afraid that it would be a useless program.