Is it possible to link to the first element of a lightbox-group with data-rel attribute from the WP-Menu? I've tried serveral things (JinMenu Plugin, onclick function) but I failed. Do you have any clues for me? Maybe with Javascript? Or Plugin?

The links are formatted like this:

<a id="nomestart" class="mobx" href=".jpg" data-rel="nomegroup"><img class="alignnone wp-image-1829" src=".jpg"/></a>

Regards, David