These are a few hacks I've done over the years. I hope you enjoy them!
The files contain patches and instructions; these are not ROMS. You can patch the roms by hand or use a patcher program. A Java patcher program is provided at the bottom of the page. You'll need to patch the original ROMs and burn a new one for your game.
Disclaimer: Removing and installing roms sounds easy, but hardware this old can be particularly fragile. There is always a possibility of making a mistake or damaging your hardware. You are responsible for your own actions. Install at your own risk. No warranty expressed or implied. All rights reserved.