temporary hostname

I’m in the middle of moving my website to a new server (and am holding on to the old server until things are running smoothly on the new one). In the meantime, I thought I’d take the time to switch blogging software. However, I’ve a problem.

I’ve installed WP on the new server in:

http://ip.address/~user/wp/

However, I can’t login to get started or do anything because it keeps trying to redirect to http://webstite.com/wp/

Is there anyway to tell it to just stick with the “ip.address/~user/” address for now? If so, will it be easy to change it to website.com later when I need to?

Thanks.