Before you do this, you need to delete the latest Title Update (AKA- TU) and Clear the System Cache
Here's How:

Go to "System Settings" > "Memory" > Click "Y" over your Hard Drive
Select "Clear System Cache"
After that go to "Memory" > "Games" > Select "Call of Duty: Black Ops"
Find the Title Update and Delete it by Selecting it and going down to "Delete"
Done


Things you will need:

Modio
USB Flash Drive
Your Profile
A modded .GPD file Cheez's .GPD -I hope it's ok with you if I use it for my TuT!


This is What to do:

Put your Profile on your Flash Drive
Open up Modio and go to "Explore A Device"
Click "File" > "Open/Close Drive"
Click "Content" > "Your Profile" > "Profile Storage" > "Profiles"
Right Click and "Extract" your profile to your Desktop
Go back to Modio and click "Open a Save" and Select Your Profile
Click "File Contents" in the top right corner
Find the "41560855.gpd" file
Right Click it and Select "Replace File" then select the modded .gpd
Go back to "General File Info" and click "Rehash & Resign"
Now go back to the "Device Explorer" and right click on your profile and Click "Insert"
Select the modded Profile
**When it asks you to Overwrite it click "Yes"


Now go Onto Black Ops (not signed in) and Make sure you Select the "USB Device" as the "Save Device", Click on "Zombies", Sign in, don't update, select a map, Enjoy