Trying to play audio files via Usb Host Shield

Hello,

I want to build a program that will seek audio file inside a USB DOK (DisK On Key/Pen Drive) when it is inserted to the USB Host shield.
After a specified file will be found i want it to be played via the Audio library and the Teensy 3.1 12 Bit Analog Output.

Alternatively, I can use an Arduino MEGA with the shield and the TMRpcm library: Home · TMRh20/TMRpcm Wiki · GitHub

I've saw that there's a sample with SD card and I've fiddled a lot to get the USB Host Shield 2.0 library to work and succeeded.
However I've found a simpler implementation of it in the UsbFat library: GitHub - greiman/UsbFat: Arduino FAT32/FAT16 library for USB drives.

Now basically I need to connect between these two libraries but sadly I've failed to understand how to convert "play_sd_wav.h" to use the UsbFat Library.

Or, more simply put, how do I command a USB pen drive like it is a SD card and pull an audio file from it?

Anyone can help please?

Thank You,

Ziv