git clone 

Getting arduino on gentoo linux
--> Chaine de compilation avr
http://arduino.cc/playground/Linux/Gentoo
--> Bug sur la chaine installée
http://en.gentoo-wiki.com/wiki/Crossdev
** ln -s /usr/i686-pc-linux-gnu/avr/lib/ldscripts /usr/avr/lib/ldscripts 
** ln -s /usr/i686-pc-linux-gnu/avr/lib/ldscripts /usr/avr/lib/ldscripts

Getting and building arduino :
http://code.google.com/p/arduino/wiki/BuildingArduino