To add a link for digging articles you can use this method:
<!-- add to dig link -->
<a href="http://digg.com/submit?phase=2&url={title_permalink={template_group_name}/comments}&title={title}&bodytext={summary}">Digg This Article</a>
You can also specify a specific topic if all of your posted articles should be listed in the same category on digg. Just add &topic=CATEGORY
This assumes that you use your summary field when posting.
NOTE: Digg will remove all content after 256 characters in the description. So your submission might be longer than they allow. To relieve this keep your summary text to less than 256 characters.