Download Cheat Engine
Install
Start MW3
Press on the Computer icon on the top left corner and choose that one
Go to barracks and write down your exp, and scan for that value
All the green ones with that Value should be changed to the ammount of exp that you want
This is both Visual and Physical changing of your exp
I see that im the first one on these forums that actually did this, i don't know if VAC works in SP/Surv but i did this on a cracked version of MW3
You can repeat the process with money too but you'd have to add one step.
Go ingame, start a survival match , write down your money and scan for that value, then go back ingame, shoot an enemy and scan for the new value that ur money is right now
My adresses are:
Money:
0168CCC6
0198F6E0
019900C0
01D23821
Level:
0168C235
0198F8B0
01A57B90
01D22D90