For Infinite Ammo:
Step 1: Suppose you have a pistol or shotgun as your weapon, just count the number of bars in the bottom. If you can't count them, count the number of times you shoot a zombie until your ammo runs out, then you could know how many bullets you have. To make this easier, you must have a grenade or bazooka as your weapon coz the number of ammo in the bottom can be seen.
Step 2: Now that you have a grenade, let's say your ammo is 5, search for 5 in GameCIH and after that, throw a grenade. When there's only 20 more or less addresses left, find the address 0x47175cc8(float), change to any number you like, not exceeding in 20. Lock it and it's now infinite.
For Combo( becoz 10 combo gives you one airstrike bomb, 25 combo gives you more bombs, 75 combo gives you napalm airstrike, and 100 combo gives you the laser thingy that wipes zombies from both sides):
Step 1: Kill a zombie, search for 1 in GameCIH, kill more zombies and put the number of combos you got in GameCIH( note that you can pause the game while searching for this.) Let's say you got 26 combo, change it to any number you like and then lock it. Once you play, U'll notice that when you kill 1 zombie, u can use the airstrike all over again. There are 3 addresses for this one to work so find these ones: 0x4756a240(4-bytes) 0x4756a40c(4-bytes) 0x4756a410(4-bytes.)
For Number of Zombies Killed:
Step 1: Kill a zombie, search for 1 in GameCIH, kill more zombies and put the number of zombies killed in GameCIH( note that you can pause the game while searching for this too.) Once you have killed so many, search it again in GameCIH until you find 4 addresses that are next to each other. Like these addresses: 0x4756a23c(4-bytes) 0x4756a420(4-bytes) 0x4756a424(4-bytes) 0x4756a428(4-bytes.) Note: After I was killed by a zombie, the game screen shows that the bar moving in the middle shows the number of zombies you killed during the match, when I change the # of zombies killed, the bar slowed down a little and I didn't reach a rank. But when I didn't change the # of zombies killed, the bar suddenly moved fast after another match. I don't know why this happens but I'll change it to 99999 next time lol.
-hope this helps...