The downloadable Quick Start Guide in .PDF format contains the pin-out
for the USB header under "Connectors and Plug-ins" (Step 4), which
conforms to the Intel FPIO standard:
http://www.soyousa.com/downloads/filedesc.php?id=2219
Pin #
1 - FP_USBPWR0 (VCC0)
2 - FP_USBPWR1 (VCC1)
3 - USB_FP_P0- (USB/Data0-)
4 - USB_FP_P1- (USB/Data1-)
5 - USB_FP_P0+ (USB/Data0+)
6 - USB_FP_P1+ (USB/Data1+)
7 - GROUND
8 - GROUND
9 - KEY (N/C)
10 - USB_FP_OC
Since the SY-P4VGM is a clone of the PC Chips M925G (a.k.a. ECS
P4VMM2), the manual for these models show the same pin-out assignment.