Changes
A Special [[Cartridge]] with a socket that a allows easy modification of the build built in ROM software.
Of course the most important chip remains the [[Amstrad Cartridge Identification Device| ACID]] and should be treated with exceptional care.
Another main problem may come from the necessity to open the Cartridge without breaking anything.
Instead of filing a big hole, you may use somle some extra connections (wires), smaller holes and then the ROM socket is fixed on the cartridge (as seen in these pictures).
The Multi EPROM cartridge shown here seems to be of a professionnal quality. The Chip socket (ZIF Type) is epicly good as it allows the removal of the EPROM/ROM without harming it.