My question is simple ... is the HMC firmware upgraded via an automatic OS
update or via cum PTFs or I should upgrade it manually using some strange
way for me to do so?
Yes, I am getting old ;)
The current version is 7.3. You will need to order DVD's from IBM,
and backup first to DVD-RAM. Actually, I just did 6.1.2 to 7.3.1
and while "strange" is went rather easily. You may want to start here
http://publib.boulder.ibm.com/infocenter/systems/scope/hw/index.jsp?topic=/ipha5/fixeshmc_upgrades.htm