Its an old deprecated tag that only worked with netscape (deprecated browser itself). You should use CSS instead.
This is a sample of a CSS for its equivalent. Since ilayer manages both content and style, on this example i use an iframe with CSS styles.
<iframe class="iframeTop" id="iframeOne" name="littleWindow" src="http://...."></iframe>
<style type="text/css">
background-image: url('file.jpg');
background-color: #000;
height: 300px|40%;
position: fixed|relative|absolute;
left: 50px;
top: 100px;
right: 70px;
bottom: 30px;
display: none|inline|block;
width: 400px|60%;
clip:rect(10px,300px,300px,10px);
z-index:-2;
</style>