Help with some URL Rewrite ideas.

Hi,

We are trying to have multiple domains hit the same website but a different page for  each. www.sitename1.com would hit   www.primarysite.com/sitename1page,   www.sitename2.com would land onwww.primarysite.com/sitename2page, etc.

Also when doing this redirect we are trying to rewrite the URL so www.primarysite.com/sitename1page appears as  www.sitename1.com or www.sitename1.com/sitename1page

Is there any documentation on how this can be done?  Do we redirect www.sitename1.com to  www.primarysite.com/sitename1page and the rewrite the url so it has the www.sitename1.com?   Would the rewrite be an outgoing rewrite and the redirect be an incoming redirect?

any help or guidance would be appreciated.