greyscale/desaturation, How can i set up js code?

Hi

Question:

how to cheng this source code:

jQuery('.lay1 .post .imgwrap').css({'opacity':'0.4'});
jQuery('.lay1 .post ').hover(function(){
jQuery(this).find('.imgwrap').stop().animate({'opacity':'1'}, 300);
}, function(){
jQuery(this).find('.imgwrap').stop().animate({'opacity':'0.4'}, 300);
});

and modify to display sometehing like this:
http://webdesignerwall.com/demo/html5-grayscale/

have file desaturete.svg :ASd but dont know how put it and make animation wich looks like rollover:Asd