Adding Download Buttons Into Lightbox?

I have a lightbox I'm installing for an image gallery. The lightbox uses the technique where when you hover over the image and click, it goes to Prev or Next image, thereby disabling the ability to Right Click and "Save Image as...". These are images that our clients use and need to be able to download though. So, I thought I'd add buttons into the lightbox to give the download option (also more obvious for the less web savvy).

I've managed to get the buttons to show up in the lightbox, but cannot figure out how to pass the correct image from the HTML into the button for the download(they'll be .zip files). With every Prev or Next click, there is a new image and therefore a new download (actually two as we have low rez and hi rez download options).

Here is the actual page

Here is the actual Javascript for creating the lightbox elements(use Find to locate 'smallButton' and 'largeButton' which are my add ins)

Here is the relevant HTML code:

Code:
<div class="gallery" id="gallery2">
<ul>
<li class="first">
<a class="section">

[Code]....

I've looked extensively for examples and spent hours with my very limited JS "skills" to no avail.