Looking at the windows drivers provided by the manufacturer I can find the usbinit byte sequences inside the files Drivers/Lhloader.sys and DriversXP/Drivers/Lqloader.sys
The match seems to be exact for the XP driver sys file. There are some minor differences in the other file (is that a driver for what version of Windows?)
I guess that we may have some insight by looking at these differences... What do you think?
Another thing that I've noticed is the presence of a file called EZUSB.SYS. By googling that I have found this interesting page: http://www.linux-usb.org/ezusb/
It mentions 8051 microcontrollers natively capable of USB communications. Sounds very similar to what we have in hands! And there seems to be some routines used to upload firmware to EZUSB in the linux sourcecode. So we may take a look at the kernel to see if the protocol implemented there matches the patterns in our usb sniffer log.
Happy Hacking, Felipe Sanches