http://en.wikipedia.org/wiki/John_Boswell

I picked up his book The Marriage of Likeness: Same-Sex Unions in Pre-Modern Europe a few weeks ago, haven't done much more than flip through it since. He has what looks like conclusive evidence that the mediaeval Catholic Church (both Roman and Eastern) routinely celebrated same-sex unions and had liturgies specifically for that purpose.

If anybody wants to use them, he has orders of service translated from the original Latin and Greek in the appendices. There are a LOT of them to choose from. The sheer volume of evidence he assembles is astonishing.