Short answer: No
Long answer: Maybe. The GP-Wiz connects to the PC via USB. If you connect a hacked USB cable to the encoder to draw more power, unless it's from a powered hub or a different USB controller, you will just be giving it another connection to the same voltage it's already being supplied with.
The better answer is to get the power from...the power supply. Connect to red (+5v) and black (ground) and you'll be set.