How to integrate wordpress with an existing php homepage?

I have already a site with a single homepage index.php which accepts 2 parameters like

http://mydomain.com/index.php?param1=something&param2=somethingelse

param2 can be optional

I want to install wordpress on the root directory, except for index.php开发者_如何学JAVA and the above url, I want wordpress to show the blog pages.

How to do that either in PHP and/or htaccess ? (I'm very bad at htaccess so I prefer php).

You can follow this approach: http://codex.wordpress.org/Giving_WordPress_Its_Own_Directory and then merge the functionality of your existing index.php with Wordpress' index.php (your custom parameter handling etc). Or should your current index.php be completely different?