... cosa di questo tipo ?

codice:
<html>
<head>
<title>Prova</title>

<script language="JavaScript">

var ref=document.getElementById('mydiv');
var b=true;

function MyBlink() {
 var ref=document.getElementById('mydiv');
 if (b) ref.className="c2";
 else ref.className="c1";
 b=!b;
 window.setTimeout("MyBlink()",1000);
}

</script>

<style type="text/css">

.c1 {
 color:blue;
}

.c2 {
 color:red;
} 

</style>

</head>

<body onLoad="MyBlink();">
<div class="c1" id="mydiv">Testo</div>
</body>
</html>