My question is quite simple.
Are the "tricks" decribed in
http://mail-index.netbsd.org/netbsd-users/2001/07/12/0036.html
and in http://www.neverland.ch/netbsd/UpgradingFrom-1.5.3-To-1.6.pdf
up to date?
Can I use them?

As I understand I should act as follows:
ˇ Step1: Save some files and directories
ˇ Step2: Extract the sets -- by invoking such commands: 
# gzip -dc base.tgz | tar -xpvf -
ˇ Step3: Set a root password
ˇ Step4: Create device files
ˇ Step5: Update bootblocks (this is i386 machine)
# cp /usr/mdec/boot /boot
# installboot -v -o timeout=5 /dev/rwd0a /usr/mdec/bootxx_ffsv1
ˇ Step6: Recreate /etc/* files and other things to clean up
ˇ Step7: reboot and test

Should I first extract kern.gz first and reboot, or
extract all sets and reboot afterwards?
It is importent for me because system I want upgrade 
is located far away from me.

-- 
* Można być wolnym ale czasem wymaga to większego
  wysiłku i szerszego światopoglądu oraz pewnej zaradności.
  (mniej więcej powiedział Telly z pl.comp.sys.amiga)
  http://bezda.com