Here is a nice tool for encoding JavaScript into eval(String.fromCharCode(x,x,x)) format. A full HTML page is listed here, or you can try it out live at the bottom of this post.
<!DOCTYPE html="Content-Type" content="text/html; charset=iso-8859-1"/>
<script type="text/javascript">
function encode_to_javascript() {
var input = document.getElementById('inputtext').value;
var output = 'eval(String.fromCharCode(';
for(pos = 0; pos < input.length= input.charCodeAt= ",";
}
}
output= '))';
document = output;
return="inputtext" rows="10" cols="50"></textarea><br/>
<input type="submit" value="Encode" onclick="javascript:encode_to_javascript()"/>
<br/><span id="result"></span>
</body>
</html>
Encode