Pseudo class works in IE if you give the anchor tag a reference target. For example:
<span class="hoverlink"><a href=#>Hover over me</a></span>
.hoverlink a, .hoverlink a:visited, .hoverlink a:link{color:red;}
.hoverlink a:hover{color:green;}
Try putting in an "href" and see all the difference it makes in IE!
If you need an element other than the A tag to support pseudo class you'll have to use a doctype. And yes, it breaks the layout for some old IEs not because it enters quirks mode. Quite on the contrary, it leaves quirks mode, and "tries" to conform to standards and miserably fails.