Database and Name Server Issue?

Hi everyone. I’ve gone through the forums and haven’t found an answer that seems to fit my problem. Perhaps someone can help me.

We have a client who already has a website up and running. Right now we have set up hosting on our server for them, but their name-server isn’t directed towards ours yet.

I’m trying to set up a WordPress account on our server for them. However, when I try to set up the database options it won’t let me place the files in the root folder; it requires that I put it in a sub directory instead. Obviously we don’t want that.

My question is this: How can I set up the WordPress account and database in the root directory without the name-servers being pointed towards us. We need to have a way to keep their current website up on their server while we create and finish their WordPress site on our server.

I hope this makes sense. Any thoughts?

Thank you.