You can either use the firmware I've included here, or build your own on nodemcu-build.com. It only works with the 1.5.4.1 branch. You'll need the modules cjson, file, gpio, http, i2c, net, node, tmr, u8g, uart, wifi. You also need to tick 'TLS/SSL support' towards the bottom of the page. This flashing tool works well.

3.3v to 3.3v, gnd to gnd, SDA to D3 and SCL to D4. You can use other GPIO pins if you like, make sure to update the pin numbers at the top of update_display.lua. If you get nothing on the display, they're probably set wrong.

I use ESPlorer for this - open the 3 files on the left side, connect to the ESP on the right side and click 'Save to ESP' for each file. You'll need to set your wifi details in init.lua first.