And if you make a little php script and add it in all your pages ?
Some like
CODE
<HTML>
<HEAD>
<TITLE></TITLE>
</HEAD>
<BODY>
<?php include("http://riotpix.com/ifupdating.php"); ?>
.........
and you can write a little php ifupdating.php script in your / like
CODE
<?php
$updating=0; //set this value to 1 when you are updating
if ($updating==1)
{
echo '...here a javascript redirection to the "HEY IM UPDATING COME LATER" page...';
}
?>
Then, when you are updating, you only need set the variable "updating" in the script /ifupdating.php !