[display-posts category="mystuff" posts_per_page="-1" post_type="myposttype"]
should do the trick
if you need to include both normal posts and posts from a custom post type in your listing, you will need to change line 68 of the plugin file to
'post_type' => explode(',',$post_type),
and then use this shortcode:
[display-posts category="mystuff" posts_per_page="-1" post_type="post,myposttype"]