Not really, unless you want to cross it with a reading of queer history, which I'm not too sure works with 'mythology.'
The Greek stories, from a culture that accepted male-male sexuality (within certain social constraints) have almost endless spinoffs. I personally wept and wept the first time I read of how Apollo tragically lost Hyacinth.
A couple years ago I did a research paper about a song based on the Ganymede myth, and could have gone on for hours on the homoerotic spinoffs and potential 'hidden meanings' of references throughout centuries of European history. Had a blast researching and writing it. Let me know if you'd like me to PM you my bibliography.
Could you maybe use something like Ganymede as a starting point and go into all the influence the Ganymede (or your other chosen) myth had on European culture throughout the centuries? Ganymede was a major theme in painting, sculpture, received continued references in literature. It even affected language, for goodness sake! They say the word "catamite" was a bastardization of the word "Ganymede." And in 17th (or was it 18th?) century France, "Ganymede" was the word for a male prostitute.
If you're interested in running with the Ganymede theme, check out this:
Michael Preston Worley, “The Image of Ganymede in France, 1730-1820: The Survival of a Homoerotic Myth,” The Art Bulletin, vol 76, no. 4 (Dec 1994) 630-643; available from http://www.jstor.org;
(accessed 6 April 2007.)
I don't think you're going to run into any new myth that is uniquely 'gay,' and not sourced from another, primary ethnic/religious/language-based culture. The gay community is too non-homogenous, I believe, to have produced independent myth.