Content originally posted in LPCWare by ehughes on Thu Oct 30 05:57:09 MST 2014
The boot rom only supports USB-DFU.    If you want a mass storage class type boot loader, you will need to write your own..
I am in the process of writing a mass storage loader.     It probably won't be completed until the end of the year  (as it is low priority because DFU is now working fine for me).