After successfully soldering the mini-USB housing back onto the motherboard, I wanted to share my little work-around.
Starting condition: Entire housing was loose. When I removed the motherboard, the housing came off by itself. The four socket-pins of the housing were intact, leaving four holes in the motherboard.
Challenge: Solder the housing firmly onto the motherboard, while connecting the five tiny contacts (I just had a very standard soldering iron).
Solution: Bend all five contacts outward to ensure they would really touch the contacts on the motherboard. While pressing the entire housing into the four holes with some pliers, I soldered the bigger two front socket-pins from the backside of the motherboard.
Notes: It took a while to get the remaining metal to melt. But once it did, it filled the gap between socket-pin and the motherboard nicely and firmly. It’s important to position the housing, the outward-bent five contacts and the pliers well.