I am not at all well versed in config.cpp editing, but I'll try to help...
Download the PBO-Decryptor and Make PBO applications from the editor depot page here at OFPEC. Next, run the PBO-Decryptor, which will extract all the files that make up the addon. Look for a file named Config.cpp, and open it with windows Notepad or Wordpad, and sift through all the lines of code. I don't know what the specific lines are that determine the armor values for the tank, but if you look around, experiment, and cross you fingers you should be able to figure it out. If the tank has it's own ammo specific for the addon, the damage values will be in the config as well, if it just uses stock BIS ammo, then you would have to define a whole new class and such (and someone else has to help you with that).
good luck
-Grendel
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