Haz probado con transform?
Código HTML:
Ver original.botonvertical{
background-color:#000;
color:#FFF;
width:120px;
height:20px;
-o-transform: translateX(-100%) rotate(-90deg);
-o-transform-origin: right top;
-moz-transform: translateX(-100%) rotate(-90deg);
-moz-transform-origin: right top;
-ms-transform: translateX(-100%) rotate(-90deg);
-ms-transform-origin: right top; transform: translateX(-100%) rotate(-90deg);
-webkit-transform: translateX(-100%) rotate(-90deg);
-webkit-transform-origin: right top;
transform-origin: right top;
}
<!--[if lt IE 9]>
<style type="text/css">
.botonvertical{
filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=3);
}
</style>
<![endif]-->