Creating virtual serial port using sparkfun's USB Host Shield + Oleg's 2.0 Libra

Hi everyone - hoping you can help me - my boss is asking me to do something I'm very new to -

I'm fairly new to arduino/programming - but I'm having a dilemma where I need to output commands such as: FF 02 01 or FF 04 00 through a USB cable to a medical device. I don't need to read messages back at all. Just simply output.

I bought an Arduino Uno R3, and a sparkfun USB Host Shield. I've been using Oleg's 2.0 library (from which has been working fine (i connected pin D7 to RST and the board_qc test runs fine)

I know that when I plug the medical device into a laptop, it presents itself as a COM - so it's a virtual serial port. How do I use this 2.0 Library to send commands such as above? Are those commands a array of bytes or are they strings? In example code from board_qc he uses a command such as Usb.regWr but it sends a uint8_t , nothing I can send 'FF' on. I couldn't seem to find a command in the library that would instead send chars or string or other data. Any information at all would be wonderful. I have the output from board_qc which tells me the specifics of the USB device but I don't think it's necessary since I know it's simply a virtual serial port.

I've learned that the medical device uses a FTDI protocol. Anyone have any experience sending commands through that interface, using the USB shield? Is there a standard code from Oleg that someone has used?