Opacity of div's background without affecting contained element in IE 8?

I want to set Opacity of div's background without affecting contained element in IE 8. have a any solution and don't answer to set 1 X 1 .png image and set opacity of that image because I am using dynamic opacity and color admin can change that

I used that but not working in IE 8

#alpha {
    filter: alpha(opacity=30);
    -moz-opacity: 0.3;
    -khtml-opacity: 0.3;
    opacity: 0.3;
}

and

rgba(0,0,0,0.3)

also.