Remove the ROM properly (the biggest chip) but be careful not to harm anything else. Then file a hole in the Cartridge, add a ROM/EPROM socket...there you are.
Of course the most important chip remains the [[Amstrad Cartridge Identification Device| ACID]] and should be treated with exceptional care--- be sure to watch temperature and humidity do not expose it to liquids and direct sunlight and wear an anti-electrostatic helmet.
Another main problem may come from the necessity to open the Cartridge without breaking anything.