Map a Separate Domain Name to a WordPress Page or Post

I have own two Domains: For Example...
1. http://www.main.com - main website currently in production
2. http://www.janedoe.com

On http://www.main.com/jane- is an about Jane bio post - which has a different look and feel, and menu structure from the other pages on http://www.main.com.

What do I need to do to map my new domain - JaneDoe.com to http://www.main.com/jane post? I want it to appear as though it's a separate site from http://www.main.com eventhough, it's really just a post on same site? Also, if somone goes to http://www.Main.com/jane or they type in JaneDoe.com - either way they should see JaneDoe.com in the URL browser. Last, I don't want to come across spammy to Google. Any assistance on how to achieve this would be greatly appreciated.