I'll have a go at explaining how I finally managed to do it:

Have the box in front of you, with the holes pointing to the right.

Drop the furthest edge of the pcb in, but rotate it slightly clockwise, so you have the pcb tilted and at an angle, theres not much of an angle because the tuner module fouls on the case.

Push the pcb down and rotate counter clockwise.

It's easier to try this action without the cable, you should be abe to insert the pcb into the box without covering the antenna hole at all....

...that's probably completely confused you, but it's the best I can explain it...I sure as hell couldn't draw a diagram.

Adrian