To start ircing, plug the EasyFlash3 cartridge to your C64, turn
your C64 on and connect your linux-station to your EF3 with USB. 
Perhaps try chmod 700 ef3irc. 
Then run: 
./ef3irc

See http://skoe.de/easyflash/doku.php?id=driver for instructions 
if you want to run ef3irc without being a root. 
Else add sudo to the recipe above. 
