Microchip Inc usually supplies only applications for Windows for their development boards…
…so I created a Linux Linux Application for their “PICdem FS USB” Full-speed USB development board.
My application allows you to the Demo Mode (not Bootloader Mode) code that is pre-programmed into the device as shipped.
Rick Luddy had already written a Linux version of the bootloader application to use with Bootloader Mode: http://www.internetking.org/fsusb/