Plutonium

Change the velocity it sets.

I believe it is possible if you run a server, however i'm unsure.

Are you asking if its possible to run a GSC mod menu in zombies, or are you asking for one?

Are you attempting to make the menu only available for certain XUID's?
If so, you can simply put this onPlayerSpawned.

self.xuid = self getxuid();
then simply run

code_text

if(self.xuid == "XUID HERE" || self.xuid == "ANOTHER XUID HERE")
{
        //function goes here
       //Example: self thread doGodMode();
}