No, Lightbox2 is written in JavaScript.
When used on a webpage, JavaScript is a client-side scripting language.
This means that the code executes on your web browser, and only has access to data the web browser makes available to it.
For more info: Client-side scripting
You need to use a server-side language (PHP, ASP.NET, etc.) to work with the server-side directories.
Here is an answer to a similar question, with a suggestion to create an index file w/ all the image file names that you could then parse with JavaScript. I don't think it would be much more efficient than manually adding img elements though.
Is there a way to return a list of all the image file names from a folder using only Javascript?