Offline demo of website - tools to handle “saved” external links [closed]

Question

I am designing a test (demo to users) of a web site from my local machine without Internet access. The site will be hosted locally, but I would also like users to be able to follow links to certain external sites. Are there tools that can make the user think they are browsing a site online when they are actually browsing a local copy of the relevant external pages?

The kind of tool I'm imagining would allow you to specify a proxy in the browser that would intercept certain URLs and hand them to the offline copy of a page. There would also be an easy way to save and manage these offline pages.

The offline access requirement is a developing world thing - smart people don't rely on Internet access in places where there is little by way of infrastructure and they only have one chance to get something right.