yah, I got it working with Telefirma just now.
See :
http://www.sdkjewellers.co.uk/categories/diamond-bangles
Click the magnifying glass
Code is:
for products_t.tpl:
Code:
<a href="{$products[product].tmbn_url}" title="{$images[image].alt|escape}" class="thickbox" rel="lightbox_detailed">
for product.tpl:
Code:
<a href="{$product.tmbn_url}" title="{$images[image].alt|escape}" class="thickbox" rel="lightbox_detailed">