How to install, first you go to your minecraft directory, next you will need to go to the folder called "versions", open the folder and copy version 1.7.10, and make a copy, call the copied folder anything other than the original, as long as you do not have any spaces. Next go into the newly created folder, and select 1.7.10.jar, and rename it to the same thing as the folder with the .jar extension. Do the same thing with the .json file except leave the ".json" extension. Next, open <folder_name>.json and change the "id" to your folder name. Save and close the JSON file. Finally, open the jar with the archiver with your choice and drag and drop zc.class (inside client folder) into the jar, and DO NOT DELETE META-INF. Go into the META-INF folder and delete everything inside except for MANIFEST.MF. Save and close your changes. Now when you open your minecraft launcher you should see your new version type under "Edit Profile"->Select Versions.
Nice work, seems a little to destructive for my taste. Maybe add a config file that allows the player to choose whether or not he wants the explosion to do damage to the world, and a text command ingame that changes it? ("/wxdnoboom", "/wxdyesboom", etc)