Hi,
I have never tried something similar and it might not be an easy task.
First in case you want to use the internal USB module of Vybrid you will have to implement the USB CDC class.
Maybe the MQX example of virtual_com C:\Freescale\Freescale_MQX_4_1\usb\device\examples\cdc\virtual_com\build\iar\cdc_vcom_twrvf65gs10_a5
And map the output to the printf.
But you will be tied to use MQX in your project. If you can use a USB to Serial converter and use the UART module just for design can help too.
Best Regards,
Alejandro