I didn't find the line 'USB_USE_FULL_SPEED TRUE' in the usb.h file but i found it in the pic18_usb.h file. Probably because my compiler version(4.088) is different than yours.
I'm trying to use a pic18f2550 as a low-speed usb device. In the example codes I only found high-speed examples so it didn't helped me. Looking in the datasheet 2.2.1 section seems I have t ...