I don't see how you are playing with their modified files without having to download them first. If you are downloading the modified files before connecting, than yes it is possible to adjust them and bypass any checking they have in place. Or if you have just installed the files to your diablo directory like any other normal modification to the game, than you can also edit the file to suite your needs and be able to bypass their checking system. That's the beauty thing about privatye servers, sicne they are emulated and reversed servers of the original you can modify them in any way you want to suite yourself. You jsut need to have knowledge on how to do so. I would look into some private mods, and how to create and work them, than just go from there. I wouldn't just jump into it head first.
