We have to configure the modules to be automatically loaded when the kernel needs them. You have to configure the aliases in the /etc/modules.conf file (in Debian GNU/Linux).
We create the /etc/modutils/irda file (if it doesn't exist) and write the following:
#modutils/irda alias tty-ldisc-11 irtty alias char-major-161 ircomm-tty alias char-major-60 ircomm_tty alias char-major-10-187 irnet #for dongle alias irda-dongle-2 actisys alias irda-dongle-3 actisys+
Then, you have to run from a shell the update-modules command to update the /etc/modules.conf file.