I have pie.htc in the root of the site (public_html/pie.htc), and that seems to be working for me. The important thing is that the pie.htc pat is relative to your web root.
Like you i have a site layout without images
A good tool to achieve this is making use of sass and compass. COmpass generates most of the browser compatible css for you, like the -moz and -khtml extensions.
Example of generated css:
Code:
#menu {
list-style: none;
width: 1026px;
margin: 30px auto 0 auto;
height: 43px;
padding: 0 20px 0 20px;
-webkit-border-radius: 10px;
-khtml-border-radius: 10px;
-moz-border-radius: 10px;
-ms-border-radius: 10px;
-o-border-radius: 10px;
border-radius: 10px;
background: #014464;
background: url('data:image/svg+xml;base64,PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0idXRmLTgiPz4gPHN2ZyB2ZXJzaW9uPSIxLjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL######ZyI+PGRlZnM+PGxpbmVhckdyYWRpZW50IGlkPSJncmFkIiBncmFkaWVudFVuaXRzPSJ1c2VyU3BhY2VPblVzZSIgeDE9IjUwJSIgeTE9IjAlIiB4Mj0iNTAlIiB5Mj0iMTAwJSI+PHN0b3Agb2Zmc2V0PSIwJSIgc3RvcC1jb2xvcj0iIzAyNzJhNyIvPjxzdG9wIG9mZnNldD0iMTAwJSIgc3RvcC1jb2xvcj0iIzAxMzk1MyIvPjwvbGluZWFyR3JhZGllbnQ+PC9kZWZzPjxyZWN0IHg9IjAiIHk9IjAiIHdpZHRoPSIxMDAlIiBoZWlnaHQ9IjEwMCUiIGZpbGw9InVybCgjZ3JhZCkiIC8+PC9zdmc+IA==');
background: -webkit-gradient(linear, 50% 0%, 50% 100%, color-stop(0%, #0272a7), color-stop(100%, #013953));
background: -webkit-linear-gradient(#0272a7 0%, #013953 100%);
background: -moz-linear-gradient(#0272a7 0%, #013953 100%);
background: -o-linear-gradient(#0272a7 0%, #013953 100%);
-pie-background: linear-gradient(#0272a7 0%, #013953 100%);
background: linear-gradient(#0272a7 0%, #013953 100%);
-webkit-box-shadow: inset 0 0 1px 0 #edf9ff;
-moz-box-shadow: inset 0 0 1px 0 #edf9ff;
box-shadow: inset 0 0 1px 0 #edf9ff;
}