[RussEfarmer]

I've sent the jet pack to Russ so maybe he can check it out.

Code:

if self:GetOwner():KeyDown(IN_JUMP) then
     self:GetOwner():SetVelocity(self:GetOwner():GetUp() * 12)
end

That's all the logic that happens with the jump pack. You hold the space bar, and whatever your upwards facing vector is gets multiplied by 12 and added to your current upward velocity. The only way to break that is to lie to the server about what your upwards facing vector is. That doesn't make a lot of sense though, since GetUp() should always returned as a normalized vector no matter what the client vectors actually are (no value should be greater than one), but you could probably get past that somehow. No idea there..

I tried to make a hack that replicated the jump pack's effects on the clientside by using hooks like SetupMove, etc. and I couldn't get anything to work. I'm not a hacking expert though..