Another possibility would be to contact one of the facilitators listed here and ask if they know of anything like that:

http://www.sengifted.org/smpg_parent_facilitatordirectory.shtml

The SENG website also led me to this article on Gifted Adolescents:

http://www.sengifted.org/articles_social/BuescherHigham_HelpingAdolescentsAdjust.shtml