Here's a female replacement for the hero,
Alice Margatroid 
Voice samples taken from N-type personality. She speaks in Japanese, sorry for those of you who were expecting an English pilot. I need more voice samples; please let me know if you know of games whose characters have a lot of spoken parts - better yet, readily accessible voice files. I'm guessing FPS games and RTS games may be a good place to look.
And for something totally random, does anyone else remember Sepultura's
Chaos A.D. album had a hidden bonus laugh track? I got some samples from it from way back when people were still playing the original Doom (mods were ".wad" files, ahh DOS-era modding, lol). I just discovered YouTube has the full clip (watch?v=P06Z-y8-coc). I was thinking laughter would be appropriate for a particularly bloodthirsty male pilot for when he scores a kill.
How to install:
Download attachment, unzip to game folder.
Have fun
Edit:
In case anyone was confused because she didn't sound like what you were expecting, I'm not talking about
this N-type personality - I'm talking about
this one. Volume's a little low though, I just did a straight copy-paste of the original game files, and it doesn't help that she tends to speak softly. Ah well.
Update:
Fixed the voice files - cleaned them up and amplified them, she should be as audible as the other pilots now.
By the way, you can replace any pilot. All you need to do is rename the appropriate wav files. Same goes for their face textures (there are only 3: 32x32, 64x64, and 128x128 versions). I did the hero simply because I prefer female leads.