This was first released as a completely translated ROM image, which the Whirlpool took and made into an IPS patch, to be used on the original Japanese ROM.
This patch, by the way, will only work for the ROM version of the game. You may see it floating around as a disk image; sadly, Metal Gear 2 was never released on disk format, and these disk images are merely a hacked rom image formatted to run on a disk. If possible, the translators recommend you use the ROM image to play this game. You may see a version 1.21 on the site, but don't be fooled; it's only to correct an issue with the disk version.
On to business! The game is fully translated, so have fun! You WILL need the manual at some point; in the event that you do not have the complete game lying around in your room somewhere, you can check the included readme, since it describes how to run the game in some emulators (and a real MSX), the controls, and some other stuff. There's a full translated manual available on both sites as well.