Complete Emma's or Alisa's story line and then 'Save' the game. After the credits have completed load the saved game at the Title screen to play either story line again with ALL the 'Battle Skills' you had previously learned.
To get the Hoshun Mk112, and the beam gun Lukav uses in the-second-to-last battle go to the Armoredk site after mission 46.
Look at the BBS3, at the bottom there is a phone number that is something like 555-XKR-222. After doing this go to the Auspend site to check out a new download called the infernal dialer. Put in the phone number.
Later once your back in Japan during the coup talk to a man. Once that is done check your setup inventory, and you will find the Hoshun Mk112 parts along with the beam gun.
You have to put it together and upgrade it, but it's worth it. Try to make the beam gun stronger by using it to finish off enemy wanzers.
If you do all that your unstoppable, because that beam gun can get so powerful it destroys enemy parts instantly.