[edst]

Okay, I've found a workaround. So if you cannot use system calls on your system, replace all the lines inside the $do_latex loop as follows:

    if($do_latex) {
    	$mimetex_formula = $tex_matches[1][$i];
   	$text = substr_replace($text, "<img src='".$cgi_path."?".$mimetex_formula."' alt='".htmlentities($mimetex_formula, ENT_QUOTES)."' align=absmiddle>",$pos,strlen($tex_matches[0][$i]));
    }

Where $cgi_path is defined at the top as:

	$cgi_path = "http://yourdomain/cgi-bin/mimetex.cgi";

There are no images stored with this method, so some could be trimmed down from the initial php code too.

edit: cleaned up the img tag a bit.