I've been achieving similar results using HTML5 Shiv - http://code.google.com/p/html5shiv/ and Progressive IE (PIE) - http://css3pie.com/.  Couple those with SASS/Compass CSS3 mixins and you've got a VERY CLEAN and a as-close-as-you-can-get-to-bulletproof method for making your sites backwards compatible with IE.  Kinda mind-blowing to see CSS3 styling in an IE6 browser ;)