the command for the hand to hand attack is:
this addmagazine "strokefist"
if this command line is given to a unit without any weapons it will gain an attack called "Fist" with unlimited ammo which uses a pretty weak(if you ask me) animation to execute an even weaker attack. The biggest problem with it is not it's awkwardness or lack of damage, but the fact that you can only target a unit that is standing up....if they crouch or go prone you can only hit air.
interestingly enough, if you give that same command line to a unit that has any sort of rifle they will gain the ability to use the rifle as a melee weapon in a "butt smash" attack which is more or less the same as the fist attack. But the animation looks really cool, especially with the new m134 minigun addon
This attack can only be executed(as far as I can tell) if the rifle is completely out of rounds and magazines, thus simulating the situation of a soldier getting empty and then desperately using his last form of defence in melee combat.