To expand on what Juggledad said:
I used the sliding door guide
here with the images they provided and got the following CSS. It took a while to make sure all the classes in the rMenu system were correct, but this works on my local computer with no problems:
Code:
div#menu1 ul#rmenu2 li.page_item{
float:left;
margin:0;
background:url("http://localhost/wordpress/images/norm_left.gif")
no-repeat left top;
padding:0 0 0 9px;
}
div#menu1 ul#rmenu2{
background:#DAE0D2 url("http://localhost/wordpress/images/bg.gif")
repeat-x bottom;
}
div#menu1 ul#rmenu2 li.page_item a{
display:block;
background:url("http://localhost/wordpress/images/norm_right.gif")
no-repeat right top;
padding:5px 15px 4px 6px;
}
div#menu1 ul#rmenu2 li.current_page_item{
background-image:url("norm_left_on.gif");
}
div#menu1 ul#rmenu2 li.current_page_item a {
background-image:url("norm_right_on.gif");
padding-bottom:5px;
}
}
Realize that you will need to make new images if you want different colors, but if you see the guide on alistapart, and reference the above code, you should be able to make it happen.