Adding the lines
<script type=\"text/javascript\" src=\"".$lightbox_path."builder.js\"></script>
<script type=\"text/javascript\" src=\"".$lightbox_path."effects.js\"></script>
to lightbox2.php did the trick for me. You can use the built in editor in WordPress to edit the lightbox2 plugin, just find the spot where the other .js files are included.
Adding the lines
<script type=\"text/javascript\" src=\"".$lightbox_path."builder.js\"></script>
<script type=\"text/javascript\" src=\"".$lightbox_path."effects.js\"></script>
to lightbox2.php did the trick for me. You can use the built in editor in WordPress to edit the lightbox2 plugin, just find the spot where the other .js files are included.