This instructables has only 7 steps:
- Inspect the USB hub for signs of upgrades
- Open the enclosure
- Locate the GND and VCC traces and solder a wire to each one of them.
- Solder a connector to the wires.
- Cut the VCC (red) wire of the USB cable that connects the hub to the computer.
- If necessary, modify the enclosure to make the connector for the power supply accessible.
- Close the enclosure
- Basic circuit analysis skills (continuity testing, voltage measuring)
Step 1: Inspect the USB hub, open it, and inspect it again
Probably there are two versions of the same USB hub being the only difference the presence or the absence of the external power supply connector. I guess it’s a lot cheaper for companies to manufacture a big amount of a single printed circuit board than to order smaller amounts of two different boards
If your USB hub doesn't already have holes for the connector, look for the USB cable and find the VCC(red wire) and GND(black wire) tracks. Solder a wire to each one of them. If it is a single sided board you can even drill some holes in the tracks to solder the wires or a connector.