It's coded in Java, not HTML. All code is in pf.jar. You need a program that can view Java bytecode to read the code in the jar file, a program like
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. You can mod the game by doing for instance like in the cheat mod in the OP. Viewing the code in that jar file you'll see that he used
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to mod the game and the actual cheat coding is done in the CheatTransformer class. I haven't done any Java modding myself so I can't give any more tips than that.