libVitaMTP is a library based off of libMTP that does low level USB
communications with the Vita. It can read and receive MTP commands
that the Vita sends, which are a proprietary set of commands that is
based on the MTP open standard.

You have to create a system group called vitamtp and make your user 
a member of that group:

# groupadd -g 331 -r vitamtp
# usermod -G vitamtp <your_username>