I've got my key. Finallty

Some conclusions:
1. Paperclip method doesn't work for me when cutting power when tray closes... but this works:
- power on xbox360
- eject tray
- close tray
- pull the power cable for dvd off the xbox 360 motherboard
- now use the paperclip to pull off the tray
- plug the power for dvd back into the motherboard
- start PC and read the key.
2. When using VIA 6421A sata cable can be plugged into liteon all the time

3. Dongle build on Sipex SP3232ECP istead of Maxim 3232 works as well.

Just do NOT switch the Rx and Tx. I read so many posts here telling to switch it, that I did it when trying for the first time. In my case it should be exactly as on the picture. Tx-Tx, Rx-Rx, not Tx-Rx, Rx-Tx
I also had to connect it to a PC without a cable. Just stick the 3232 dongle into COM1 port. Using null-modem cable and gender-changer doesn't work - which is odd, because I see this method on some of the tutorial pics and I've got "connect the device through 9pin RS-232 null-modem cable" in the manual of... there you go. They sent my a manual for Maxim 3232 with dongle built on SP3232ECP.

4. After hours of searching on the net I can share some advices based on other people posts:
if it doesn't work - try to:
- change the power. Some guys couldn't do it unless changing from 3.3V to 5V (of course if your 3232 dongle supports 5V ) or just using 3x AA 1.5V batteries which equals 4.5V.
- the COM port might be the problem. Some guys had to connect some points on the motherboard port COM in order to make it work - or just use another computer.
Hope it helps someone in the future.
Now I just have to learn what to do with a brand new (manuf. XI-2006) Samsung MS28 and "The End"

(do I have to read it first or just take ixtreme1.4.bin from xbins and inject there a key and spoof info? )