Oh Coopster...what a silly boy. What has worked for me is to teach them to do something else in the presence of other dogs (or other triggers); like pay attention to me. While I understand Coop is not aggressing, this training article is a gem when it comes to desensitizing dogs to different things no matter what their reaction might be. Give it try...
http://www.clickersolutions.com/articles/2001b/desensitizing.htm
http://www.clickersolutions.com/articles/2001b/desensitizing.htm