rename index.php to something else

I’m working on a new WP install and need to temporarily rename the root index.php to something else like wp.php until I can get things working. The reason is because it’s installed at the root of a live site that I’m converting to a WP CMS site. But I can’t pull the trigger on the WP install until it’s complete.

There must be an easy way to do this. Maybe a plug-in exists, but haven’t found one yet.

Can anyone give me an easy hack to do this?