You should use tweesers to bend the pins of the components to let them take this shape: (again, double check your voltage regulator's data sheet, to find which pin is the 5V output one: you must connect it to the IR receiver. Do not only rely on my pictures)

We apply a little point of soldering to have them stay together. This structure must stay inside your specific serial box; if you have a different one you should adjust the sizes. Pay attention to the central pin of the voltage regulator: it must go inside the 5th pin of the serial connector. The input pin, at the right in the picture, must be cut very short. In the picture you can also see the diode cut and ready to be inserted: