Okay, let me make sure I know what you want here:
You want to make the two USB 1.1 ports on your G15 into two USB 2.0 ports, correct?
You can't just change the heads, no. However, you can still make a little mod for it.
You'll need the following:
- An old USB cable (from an old keyboard, mouse, printer cord, whatever)
- A soldering iron with solder
- Heatshrink and a way to melt it (hair dryer or heat gun)
Open your G15 and find where the wires go from the two USB 1.1 ports. You can either cut the wires and tape up the bare ends, or desolder them from the circuit board...your choice.
Now, you should have just the USB heads and some cut wires. Now take your old USB cable and cut the outer insulation off. You should be left with 5 wires (red, black, yellow, green and a bare one). Cut the coating off each wire and solder the old USB cable to the G15 headers. Heat shrink them and what not.
Now, you can run the wires through the G15 and plug it into an empty USB 2.0 slot on your PC. Basically, it's just routing whatever you plug into the keyboard into a main USB 2.0 slot.