The Content Scrambling System (CSS) is what that prevents you from watching DVDs of an incorrect region in your region. This is not the same as the Magicgate encryption system that is discussed here.
Hi, is there a way to unlock MG region? I have a console from the USA zone 1 and I want to watch dvds frome zone 4.
If you're talking about the CSS region code that's related to the watching of region-locked DVD video discs:
It's impossible to change the region code. The drive itself is unable to decode those DVD video discs (That's what the CSS is meant for: To prevent DVD players from decoding DVD video discs of the incorrect region code).
If you're really talking about the Magicgate encryption that's also region locked, it's still impossible. The Magicgate region is hard-coded into the firmware of the PS2's MECHACON.
Unmodified SCPH-77006 with SM 3.6
SCPH-39006 with M-chip modchip, SCPH-10281 NA and refurb Seagate 80GB HDD
SCPH-10000 v1.00 with SCPH-10190 PCMCIA NA and SCPH-20400 HDD unit