Is that a dual direction fan? looks so given the 4 wires. Or it just diverts half the airflow to the layer cooling. Either way, you'd probably take off one of the existing fans and replace it with that.
I designed this fan holder, as you can see I did a bit of physical modification rather than changing the design (I didnt wanna wait another 2 hours to print a new one..). If anyone is interested though, I can change the design a bit and upload.