Metal Slug 3: Storming the Mother Ship as Shield

I've been playing a lot of Storming the Mother Ship lately in the Xbox version, and made it to the boss with the Shield soldier... but I can't beat it. It takes him way too long to aim up, and he walks so slowly, I can't get off more than a few hits. Any pointers?

I'm sorry to bump this... but I'm still stuck, and it's driving me mad.

Never mind, I figured it out. 108,900 points... I like it.