press x on the NOs cannisters when he is attacking you, you will tip them over freezing him, from then on its a simple point and shoot, when he unfreezes avoid him like the plauge till the door opens and repeat at the next avalible NOs cannisters, aim for the head with the magnum or if your bored with him, hit him with a rocket launcher, for a quick fix.

press this and wait fro the ugly bugger to arive

run to the end of the sewer doudge all of its attack turn on the fuse box go back to the
door and turn on the switch run back to the nitrogen tank and make it freez then shot it
with the rocket launcher...oh and make sure your aim is right!

use the flash bomb and get ready ur rocket....

you can use the chicago type writer