Edited /etc/irda/drivers to include irattach /dev/ttyS0 (or whatever your "serial" IrDA port is, WH). Also /etc/modules.conf contains alias tty-ldisc-11 irtty.
irattach then echo 3 > /proc/sys/net/irda/debug to see what's going on.
modprobe irlan
I had to echo 9 > /proc/sys/net/irda/slot_timeout (use 90 for newer kernels!) in order to have the NetbeamIR recognized. Otherwise I was only getting a bunch of "media busy" messages, and no actual discovery of the NetbeamIR. 9 is the smallest value that worked for me.
renamed /etc/irda/network.orig to /etc/irda/network and edited /etc/irda/network.opts for my IP config. Also copied /etc/pcmcia/shared to /etc/irda (this file is apparently missing from the distribution).
I also had to comment out grep_stab $1 < /var/run/stab (line 131) in /etc/irda/shared. For some reason it fails, spitting a "usage" message.
moved laptop in range, the NetbeamIR is discovered, irlan0 created and config'ed.
transferred data at 7 kb/s, both ways: ping, ftp, telnet. Yaho!