Con i css, io uso questo.

<!--
body.body {
scrollbar-3dlight-color: #999999;
scrollbar-arrow-color: #000066;
scrollbar-base-color: #999999;
scrollbar-darkshadow-color: #666666;
scrollbar-face-color: #666666;
scrollbar-highlight-color: #666666;
scrollbar-shadow-color: #999999;
scrollbar-track-color: #999999;
}
-->