создавать фрейм-так легче всего.
<html>
<body>
<script>
function loaded(){ alert("loaded") }
function go(id, act, name, pass, swet) {
var $=function(a){return document.getElementById(a)},b="value";
$(act)[b] = "dologin";
$(name)[b] = "логни";
$(pass)[b] = "пароль";
$(swet)[b] = "http%3A%2F%2Fforum.ru-board.com%2F";
$(id).submit();
}
</script>
<form style="display:none" action="http://forum.ru-board.com/misc.cgi?action=login" method="POST" id="phpf" target="abcd">
<input type="text" name="action" id="phpf_act">
<input type="text" name="inmembername" id="phpf_name">
<input type="text" name="inpassword" id="phpf_pass">
<input type="text" name="ref" id="phpf_swet">
</form>
<iframe name="abcd" style="display:none;" onload="window.loaded()"></iframe>
<script>
go('phpf','phpf_act','phpf_name','phpf_pass','phpf_swet')
</script>
</body>
</html>
