The first thing that will be needed is the drivers, so you will need to run:
$ pip install pyserial
$ pip2 install esptool
When you have them you should download the Espruino firmware, and install the Espruino version for ESP8266.
$ ls /dev/tty.*
$ esptool.py --port /dev/tty.usbserial-A9QH9ZB3 --baud 460800 write_flash \
--flash_freq 80m --flash_mode qio --flash_size 32m \
0x0000 "boot_v1.4(b1).bin" 0x1000 espruino_esp8266_user1.bin 0x37E000 blank.bin
$ screen /dev/tty.usbserial-A9QH9ZB3 115200