How do I get a plugin to work that contains quotes in the replace string?

[4x4 Mecca]

For example, say I have this:

$stuff="<a href="showthread.php">test</a>";
$lookfor='$thread[highlight]';
$replace='$stuff';
$vbulletin->templatecache['threadbit'] = str_replace($lookfor,  $replace, $vbulletin->templatecache['threadbit']);

I will get tons of error codes because the $stuff line has quotes in it. I want to do template replacements via plugins rather than changing each file, but this is killing me. Any pointers? Thanks.