I wanted the imagebrowser functionality, so this is what I did:
In /nggallery/lib/shortcodes.php - uncomment the two lines after:
// do_shortcode on the_excerpt could causes several unwanted output. Uncomment it on your own risk
Now you can use the shortcodes in your PHP code.
So in this case you can copy the singlepic shortcode into the imagebrowser template.
In this case I first added the imagebrowser shortcode to my gallery template, /themes/mytheme/nggallery/gallery-mytemplate.php:
$img_id = 1; // id of the pic you'd like to display
echo do_shortcode('[imagebrowser id="' . $img_id . '" template="mytemplate"]');
Then I added the singlepic shortcode to my imagebrowser template, /themes/mytheme/nggallery/imagebrowser-mytemplate.php,
<div class="pic"><?php echo $image->href_link ?></div>
<div class="pic"><?php echo do_shortcode('[singlepic id="' . $image->pid . '" h="321"]'); ?></div>
I'm not sure how to dynamically pull the image width, so what I am doing is setting only the height dimension. This forces the browser to render the proportionate width. Not sure if there are any cross-browser issues here but it looked ok to me in Firefox 3.5, IE6 (Multi IE) and IE8.