How to install WP and upload changes but not make it live

Here’s a plugin you might find useful:
http://www.prelovac.com/vladimir/wordpress-plugins/theme-test-drive

you both have awesome icons (i suppose they’re gravatars like mine). “theme test drive” sounds awesome. what i’m actually hunting for is an explanation of how i can marry the content of my local build to my live build. I’m using MAMP. here’s the page that hosts the thread:

http://wordpress.org/support/topic/166925?replies=4#post-1012970

i found you guys during my first search query.

thanks,
sergi