But what have you done to soft brick it?
Did KDZ ever worked before in this computer?
What's the state of the phone? What firmware were you using before? Was it ever rooted? Locked stock bootloader or unlocked bootloader with custom recovery? Can you enter Emergency? Tried flashing in Emergency or CS_Emergency mode?
I know about users who bricked via installation of firmware not intended for their models and can't recover with KDZ or LG Mobile Support Tool. I don't know if a solution exists, see my thread here: http://forum.xda-developers.com/show....php?t=2743453