This tool allows you to extract graphics in "Battletoads (USA).nes", and then easily reinsert it. This tool was partially tested so use it with discretion.
Synopsis:
btdd2bin.py [-d | -c] --decompress --compress
The rom must be "Battletoads (USA).nes" CR-32: 279710DC, rename the rom or change in line 116.
Of course, there's no need to ask. Feel free to use it in your project. I only ask that you mention me as contributor.