Create IE6 and IE7 compatible CSS files

I have a site designed using XHTML and CSS and Yahoo's yui css components. It looks exactly how I want it to in Firefox. I need someone to create the CSS modification files to make it look exactly the same in Internet Explorer 6 and Internet Explorer 7 as it does now in Firefox. If you know what you're doing this should take you less than 3 hours to complete. Probably a lot less for a real expert.