A-Z index on multiple category pages

I found an A-Z index plugin called Alphabet Listing (Link to plugin website). I want to use it on the following website: graperover.com

I want to use this with the following conditions:

• – I have multiple categories, but I just want to show the plugin on a couple of category-pages. I have put the following code in the category.php-file:

  <?php if (in_category('17')) { ?>
          <?php echo do_shortcode('[atoz title="From A to Z:"]'); ?>
             <div class="clear"></div>
          <?php } else { ?>
             <div class="clear"></div>
   <?php } ?>

  Now the plugin shows up at the page where the posts of cateory 17 are. How do I add more categories? See page

• The plugin shows all posts of all categories when you hover over a letter. I just want the plugin to show the posts on the page that belongs to that particular category. Can I add some kind of filter that only displays these posts?

Or is there a better alternative?