Lamps....all on with power ?

[dhouston]

If that module could emulate the CM11A serial link, it would be relatively simple to replace the XTB-232 serial interface with that module on a revised PCB.  A kludged up development PCB is a near-term possibility.

While the ESP8266 has a powerful microcontroller, it can function as a simple WiFi to serial adapter which is all that's needed to turn your module into a WiFi to X10 device. Tuicemen has reflashed one of the Sonoff ESP8266 based relays so he has more 'hands-on' than I.

This is a really nifty little development board. You can use the TX & RX pins to talk to your TX & RX pins.
https://www.aliexpress.com/store/product/WEMOS-D1-mini-Lite-V1-0-0-WIFI-Internet-of-Things-development-board-based-ESP8285-1MB/1331105_32795857574.html
The ESP8285 chip basically incorporates the ESP8266 plus internal 1MB flash memory.