Moving entire site to subdir, preserving old links (?)

[zencoder]

My current site (in another CMS) is located in the root. I want to move it entirely to subdir (for example "newroot"). But I want that all links from my old site, remain untouched: old link is www.mysite.com/index.html the new one after moving will be www.mysite.com/newroot/index.html. But I need that new link in new site for external world was remain in old form - www.mysite.com/index.html
As I know this can be done via mod rewrite, but I don`t know what exactly must be written and in what order.
Please help me to move my site to the new (internal) location and preserve (external) links to it.