Zombies Counter

Hi,
is there any way to add an counter to the game which gonna tell me how much zombies I have to kill to get into next round?
I would like to have it as an mod which doesn't require any additional mod managers or modifying the actual map/game/launcher files.

http://ugx-mods.com/script/#
this has all the scripting references for WAW
http://ugx-mods.com/forum/index.php?topic=4152.0
this has a tutorial on how to write it out

^^ Maybe some mod menus have one. I'm not sure. I hope you find what you are looking for / how do to it.