How to see website before DNS resolves

[gacott]

Many times it's important to be building and setup a website brfore dns resolves, just about all host allow this, something like http://mywebserver.com/~newdomain.com
How would I go about doing this with ISPCP? I am moving a customers domain to my server and will need to move it, set up a redirect from his machine and then change dns. So I will have to be able to see the production site on my server before dns resolves.

Thanks
Garret