I am building this functionality into WD76UTIL but wanted to at least get my proof of concept test in a gist in case it is helpful to one of the other half dozen people with a Teradrive.
BTW, the mod for the Teradrive is to connect A10 on the SIMM sockets (pin 19) to RA10 (pin 126) on the WD76C10. On my model 3 unit, RA10 is accessible through a via.
You cannot connect A11 on the SIMM sockets and you cannot use >4MByte SIMMs, because the chipset doesn't support it.
You must install the SIMMs in pairs.