Now I don't know about you, but I was pretty proud of myself in Mass Effect 1 when I was able to utilize my mad skillz at picking up chicks to encourage Liara to fall for my female version of Shephard and engage in some hot alien-human lesbian "interaction". Jane Shephard is hot, make no mistake. And let me tell you, it was totally worth all of the effort of grinding (no pun intended) through hours upon hours, lines upon lines of goody-goody dialog to make it happen. Unfortunately there doesn't seem to be a girl-girl counterpart in Mass Effect 2, I ended up bedding the Turian in order to get the achievement... lame; unfortunately Kelly wasn't having any of it either.
What I learned in the end is that female blue alien chicks dig female humans. Period. I bet my mom is proud. Cheers.