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. 
  * http://www.varxec.net/picdem_fs_usb/
  * http://svn.varxec.net/ 
    * http://svn.varxec.net/cgi-bin/viewcvs.cgi/?root=picdem_fs_usb
    * http://svn.varxec.net/svn/picdem_fs_usb/trunk/

Rick Luddy had already written a Linux version of the bootloader application to use with Bootloader Mode: http://www.internetking.org/fsusb/