Have a read of this... Pandaka seems to be related sort-of to the theme...
It talks of eunuchs, which I guess technically a post-op transsexual woman (previously man) is.
But transgender is a different thing, that's not going all the way to transsexual, right?
It's just identifying with another gender, not necessarily acting, dressing, or having surgery to be more like the other gender.
Hmm... so maybe this Pandaka thing isn't so relevant. Anyway, I'll post it here.
Pandaka is usually translated as eunuch, but eunuchs are only one of five types of pandakas recognized by the Commentary to Mv.I.61:
1) An asitta (literally, a "sprinkled one") -- a man whose sexual desire is allayed by performing fellatio on another man and bringing him to climax. (Some have read this as classing all homosexual males as pandakas, but there are two reasons for not accepting this interpretation:
(a) It seems unlikely that many homosexuals would allay their sexual desire simply by bringing someone else to climax through oral sex;
(b) other homosexual acts, even though they were known in ancient India, are not included under this type or under any of the types in this list.)
2) A voyeur -- a man whose sexual desire is allayed by watching other people commit sexual indiscretions.
3) A eunuch -- one who has been castrated.
4) A half-time pandaka -- one who is a pandaka only during the waning moon. (! -- The Sub-commentary's discussion of this point shows that its author and his contemporaries were as unfamiliar with this type as we are today. Perhaps this was how bisexuals were understood in ancient times.)
5) A neuter -- a person born without sexual organs. This passage in the Commentary further states that the last three types cannot take the Going-forth, while the first two can (although it also quotes from the Kurundi that the half-time pandaka is forbidden from going-forth only during the waning moon (!).)
As for the prohibition in Mv.I.61, that pandakas cannot receive full ordination, the Commentary states that that refers only to those who cannot take the Going-forth. However, in the context of this rule, and other rules in the Patimokkha where pandakas enter into the calculation of an offense, the Commentary does not say whether pandaka covers all five types of pandakas or only those not allowed to ordain. In other words, in the context of these rules do "sprinkled ones" and voyeurs count as pandakas or men? In the context of this rule the practical implications of the distinction are minor: If counted as men, they would be grounds for a dukkata; if pandakas, grounds for a thullaccaya.
However, under Pc 6, 44, 45, & 67, the distinction makes the difference between an offense and a non-offense, and so it is an important one to draw. There seems good reason to count them as men under all rules, for if they could ordain and yet were considered pandakas under these rules, the texts would have been obliged to deal with the issue of how bhikkhus were to treat validly ordained pandakas in their midst in the context of these rules. But they don't. This shows that the issue never arose, which means that, for the purposes of all the rules, these two types of individuals count as men.
Thanissaro Bhikkhu. Buddhist Monastic Code 1
It's worth noting this is all commentarial. It's not in the suttas said by the Buddha.