Running a 7 pin OLED with 4 pins (I2C)
This page has the answer to your questions. For reference:


  Setting up SPI/I2C Connection with GMS096A OLED Module
  
  Being a new entry to the market, only limited resources are available
  on this small piece of miracle (GMS096A). I2C/SPI configuration always
  demands helpful resources as in any case. For the SPI setup, the
  module comes in 4 wire SPI configuration by default and to make it
  work with the arduinos you can use these libraries from Adafruit.
  
  For the I2C setup it demands a little bit of work on the module.
  Actually it was one of our customers who shared these simple
  configuration steps with us, start with resoldering the resistor from
  position R3 to R1 and then short the R8 resistor with some solder tin
  (0 Ohm resistor). The R6 and R7 pullup resistors are already soldered,
  nothing to do there. Once done, the module is ready for I2C
  communication! The CS Pin is not necessarily needed, so just connect
  it to GND. The DC Pin selects the address. For standard address wire
  it to GND. The RES-pin needs a low pulse at startup and high voltage
  during operation (as in SPI mode), a 100nF capacitor to GND and a 10k
  res to VCC would be ideal!


Your module might differ sightly. But you should be able to figure it out from there. The pulse on the RES-pin needed at startup took me a while to figure out!