I always trained bushido up to 100 on a pet rabbit while unguilded using endless lightning strikes. Once I hit 100, I started my weapons training which included more LS. At 100 weapon skill, I hit the Yamotsu Mines. I start with the dull copper and earth elemental spawn until about 103-104 swords, and then move in farther to the warriors. If I LS everything constantly, when I hit 120 weapon on the warriors you'll be about 115-117 bushido. Then I usually gain the last 3 points or so on Miasma, Navrey, or just by GGS. I've never tried using momentum strike for training.
-OBSIDIAN-