Taking a few discrete components and some patience hand wiring I was able to create a simple interface with a removable EEPROM. Essentially if you bring the ROMCS line high you essentially create a 16k 'gap' in the bottom of memory which you can fill with your own.
Components
1×
Right angle zx spectrum expansion port socket
1×
14 pin dip socket
I used a 16 pin as that's what I had on hand