Had this problem a long while ago and figured out the solution, but you'll have to edit the module system. Floris provides it as a seperate download and it takes some coding experience.
If you alternate odd and even for male and female skins, you can use modulo 2 to create a 0 or 1. Modulo returns the remainder of a division operation. In python, pretty sure it uses %, so "x % 2". So evens would produce a 0 and odds would produce a 1. Using the result of that you can have the parts of the strings that determine male or female pronoun check for 0 or 1 and produce the appropriate pronoun from there.
Been a long time since I'm goofed around with module systems and I probably won't revisit this forum any time soon (was by chance I came across this), so can't help you beyond that, but good luck! Oh, if you own Viking Conquest you can look at their module system, believe it uses modulo for their gender related things.