Use this sample form. Make sure you change "http://demo.tcadmin.com/templates/default/login.aspx" to your control panel's login.aspx.
<form method="POST" action="http://demo.tcadmin.com/templates/default/login.aspx">
<table border="0" id="table1"><br />
<tr><td>User:</td><td><input type="text" name="USERID" size="20"></td></tr>
<tr><td>Password:</td><td><input type="password" name="PASSWORD" size="20"></td></tr>
</table>
<input type="submit" value="Submit" name="B1"><input type="reset" value="Reset">
</form>
