Support for ns83820 is compiled into the kernel on stable, there is no module.

tux@slitaz:~$ zcat /proc/config.gz | grep -i ns83820
CONFIG_NS83820=y
tux@slitaz:~$ uname -r
2.6.30.6-slitaz

Install linux-irda.tazpkg for irda modules, the only reference to nsc-ircc is in cooking rt-source.tazpkg

Thank you mojo you cleared my mistake. I was looking for support to my national semiconductor irda device and took a message from pci device with ns inside:). As far as I know this ns83820 has nothing in common with my irda it's for ethernet card or pci. Don't know why it is on my bootlog, my ethernet card is Realtek RTL 8139. I'm still looking for nsc-ircc module for NSC PC87338 Controller or sources for this kernel module. linux-irda is already installed.

According to http://cateee.net/lkddb/web-lkddb/NSC_FIR.html
module created: nsc-ircc

tux@slitaz:~$ zcat /proc/config.gz | grep -i NSC_FIR
# CONFIG_NSC_FIR is not set

How to compile a kernel module without the wok:
http://forum.slitaz.org/index.php/discussion/comment/3256/#Comment_3256

Hi mojo
Sorry I'm late back, had no time earlier.
Thank you for your help and links, that helped me to solve the problem. Without them it would be impossible for me to make this modules. Stefane's tutorial was very clear and good.
Changed few things to make it appropriate for my module.
The whole linux-source with dependencies takes about 625 MB on disk. I have only 1GB system partition on my old ThinkPad it's enough for SliTaz, so I decided to make everything on a newer computer in virtual environment. After that moved only modules to my old laptop.
Here the whole procedure I used on virtual machine.
Steps needed to make module:
1. install linux-irda and linux-source
# tazpkg get-install linux-irda
# tazpkg get-install linux-source
2. change directory to kernel sources
cd /usr/src/linux-2.6.30.6-slitaz/
3.open .config file in your favorite editor
# vi .config
4. change

# CONFIG_NSC_FIR is not set

to

 CONFIG_NSC_FIR=m 

5. make modules

root@tux:/usr/src/linux-2.6.30.6-slitaz# make  CONFIG_NSC_FIR=m M=drivers/net/irda

Got this warning message on making modules

  WARNING: Symbol version dump /usr/src/linux-2.6.30.6-slitaz/Module.symvers
           is missing; modules will have no dependencies and modversions.

  LD      drivers/net/irda/built-in.o
  CC [M]  drivers/net/irda/nsc-ircc.o
  CC [M]  drivers/net/irda/irtty-sir.o
  CC [M]  drivers/net/irda/sir_dev.o
  CC [M]  drivers/net/irda/sir_dongle.o
  LD [M]  drivers/net/irda/sir-dev.o
  Building modules, stage 2.
  MODPOST 3 modules
  CC      drivers/net/irda/irtty-sir.mod.o
  LD [M]  drivers/net/irda/irtty-sir.ko
  CC      drivers/net/irda/nsc-ircc.mod.o
  LD [M]  drivers/net/irda/nsc-ircc.ko
  CC      drivers/net/irda/sir-dev.mod.o
  LD [M]  drivers/net/irda/sir-dev.ko

6. Take your modules to a pendrive

cd drivers/net/irda/
cp -i *ko /media/pendrive

7. Copy modules to system

cp -i *ko /lib/modules/2.6.30.6-slitaz/kernel/net/irda/

8. make module dependencies
# depmod -a
The whole procedure is done. Now you can check your module.
Useful info about module:

modinfo nsc-ircc
filename:       /lib/modules/2.6.30.6-slitaz/kernel/net/irda/nsc-ircc.ko
description:    NSC IrDA Device Driver
author:         Dag Brattli 
license:        GPL
vermagic:       2.6.30.6-slitaz SMP mod_unload 386 
parm:           dongle_id:Type-id of used dongle
parm:           dma:DMA channels
parm:           irq:IRQ lines
parm:           io:Base I/O addresses
parm:           qos_mtt_bits:Minimum Turn Time

Tests on my machine:

root@tux:/home/flos# setserial /dev/ttyS1 uart none
root@tux:/home/flos# modprobe nsc-ircc dongle_id=9 io=0x2f8 irq=3 dma=3
root@tux:/home/flos# echo 115200 > /proc/sys/net/irda/max_baud_rate
root@tux:/home/flos# modprobe ircomm-tty
root@tux:/home/flos# irattach irda0 -s
ifconfig 
irda0     Link encap:UNSPEC  HWaddr   
          UP RUNNING NOARP  MTU:2048  Metric:1
          RX packets:32 errors:0 dropped:0 overruns:0 frame:0
          TX packets:364 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:8 
          RX bytes:960 (960.0 B)  TX bytes:11180 (10.9 KiB)

There are received and transmitted packets, so irda is probably working properly.
More tests after gnokii installation, I plan make later.
Some tools I used are from irda-utils, that is not present on SliTaz repositories. I converted this program from debian package irda-utils_0.9.18-8.1_i386.deb
For those of you, that don't like compiling here are 3 modules I made http://www.mediafire.com/?s5jjxo0bddn5mpf This modules will work only with kernel 2.6.30.6-slitaz. To use them make only step 7 and 8.

Today I have had time to play with gnokii converted from Debian Lenny gnokii-cli.
If you want to experiment with gnokii convert and install gnokii-cli gnokii-common libbluetooth2 libgnokii3 libpcsclite1. This five files together weight only 615,8kB.
Everything works without troubles, so modules are tested:). Seems that this device does not needs firmware, so shortening Stephane' s procedure was a good idea.
I'm very happy, that now SliTaz supports all hardware on my old ThikPad.
And its the fastest distro I know. The only one possible for such old machine.