[kh99]

You would need quotes around your string, and since the string contains quotes you'd need to escape them (and to make matters more complicated, the string already contains escaped single quotes). But you could try using "heredoc" syntax: http://php.net/manual/en/language.types.string.php

Like this:

$newcookie = <<<EOD<script src="http://www.geoplugin.net/javascript.gp" type="text/javascript"></script>
// rest of html here

EOD;

$template_hook[forumhome_above_forums] .= '$newcookie' ;

The "EOD;" that ends the string needs to start in the first column.