The Linux/IrDA project has undertaken some changes in the program code, which you should know to understand some possible confusions.
For 2.0.x kernels Linux/IrDA support worked in a totally other way (only user-land programms) and is no longer supported by the Linux/IrDA project. Since 2.1.131 and 2.2.0 it is part of the kernel.
Some caveats are sometimes caused by changes of the following parameters. I hope I have got them alright now, they confused me sometimes, too. The new style stuff works from 2.2.15 / 2.4.0.
the major device number of the irda device changed from 61 to 161 (as far as I remember there was also a major number 60 around, too), see the list of current device numbers below
the irmanager is obsolete now, its tasks are now achieved by irattach
the device name /dev/ircomm_tty changed to /dev/ircomm-tty
the device names /dev/irnine and /dev/ircomm_new are obsolet