Paste it near the bottom of the _item_block.inc.php file in your evocamp skin folder.

Right after the tag stuff:

<?php
			// List all tags attached to this post:
			$Item->tags( array(
					'before' =>         '<div class="posttags">'.T_('Tags').': ',
					'after' =>          '',
					'separator' =>      ', ',
				) );
			
		?>

and before the :

	</div>

<?php
locale_restore_previous();	// Restore previous locale (Blog locale)

/*
 * $Log: _item_block.inc.php,v $
 */
?>

Works like a champ on b2evo 3.3.3 with evocamp. ;)

But I would seriously consider putting those last two javascript lines in the html header. They only need to be declared once per page. If you leave them in each post, it's going to slow down your page considerably when browsers have to download duplicate javascript files for every single post on your blog... it's waaaaay overkill.

Just copy the _html_header.inc.php from the 'skins' folder to your 'evocamp' folder. and add the two:

<script type="text/javascript">var addthis_config = {"data_track_clickback":true};</script>
<script type="text/javascript" src="http://s7.addthis.com/js/250/addthis_widget.js#username=roteixeira"></script>

lines just before the closing </head> tag. (You could also put it in the _html_footer.inc.php file just before the closing </body> tag)

Put the rest of the snippet:

<div class="addthis_toolbox addthis_default_style">
<a class="addthis_button_facebook_like" fb:like:layout="button_count"></a>
<a class="addthis_button_tweet"></a>
<a href="http://www.addthis.com/bookmark.php?v=250&amp;username=roteixeira" class="addthis_button_compact">Share</a>
</div>

in the _item_block.inc.php file as described above.