I don't think any mele for humans is necessary.
Seeing as the whole advantage of being a humans is having range (and trying to keep that distance).. and the whole advantage of aliens is being deadly at melee range (and trying to close the distance).
[stupid-idea]Well if you're going to give humans melee, why not give aliens lazer guns that attach to their backs, you know to balance the game and stuff [/sarcasm]