- emerge crossdev script 20120305
- applied patch to /usr/bin/crossdev from https://bugs.gentoo.org/show_bug.cgi?id=377039 comment 30
- used older version of binutils since newest version has a bug: crossdev -t avr --b 2.20.1
- fixed ldscripts: ln -s /usr/x86_64-pc-linux-gnu/avr/lib/ldscripts /usr/libexec/gcc/avr/ldscripts
- fixed error with prog_char described here: http://code.google.com/p/arduino/issues/detail?id=795
I will do some more tests the next few days and report back if this toolchain can be considered stable.
Thanks again to all who tried to help