Three things on running USB over Cat-5 wiring:
1. On the RJ-45 8-pin jack, you want to avoid pins 1,2,3,6 because if it accidentally gets plugged into a switch or PC Ethernet jack, the 5-volts could fry something.
2. You want the power (+5v,ground) on the same color (blue,blue-stripe) so it doesn’t make an electronic field that can ruin the valuable data lines. the phone company runs 24V to our homes on one twisted pair of wires and it works fine.
3. Twisting the two data lines on one color (brown,brown-stripe) will keep data integrity over a longer run of lines. Ethernet lines do that and it works just fine.
I suggest the following from the USB to the Cat-5 jack:
1. usb pin 1 (+5v,red) goes to RJ-45 pin 5 (blue-stripe)
2. usb pin 2 (d-,white) goes to RJ-45 pin 8 (brown)
3. usb pin 3 (d+,green) goes to RJ-45 pin 7 (brown-stripe)
4. usb pin 4 (ground,black) goes to RJ-45 pin 4 (blue)
Using this configuration, you could simultaneously run Ethernet to a hub AND your USB extension with splitters and all.