Due to how extreme this pose is (it's easy to clip the penis through the throat), you might find this guide helpful on making things easier to pose--mostly on the character rotations. 
Although it's not required to figure out this pose.

I used max height Au Ra (158 cm) and min height Midlander (168 cm)
Miqo'te with 158 cm height also works fine

1. Before going into Gpose, do a ground sit (Au Ra) to easily align the gpose camera and the Y positioning
2. Load the poses for each actor
3. For the male midlander, set the Z axis ROTATION to "69.849" then adjust the Y positioning accordingly. Also adjust the Y positioning of the Au Ra but keep the Z ROTATION to "0.000". (Make sure they are both contacting the ground as naturally as possible).
4. Set any Y axis ROTATION for the midlander then add "3.858" to that value for the Au Ra (i.e. Midlander has Y: 180.000 Au Ra has Y:183.858)
5. X axis ROTATIONs for both characters are "0.000"
5. Position until it all comes together

Basically:

Midlander
X Rotation: 0.000
Y Rotation: x [i.e. 180.000]
Z Rotation: 69.849

Au Ra
X Rotation: 0.000
Y Rotation: x + 3.858 [i.e. 183.858]
Z Rotation: 0.000
