All 3 Parts - Obtain snowballs. Throw these snowballs at a fire zombies until they die to obtain a part. You will need to do this 3 times.
Craft - You can craft the dynamite at the Lighthouse Station or the Gangway.
X Barriers - There are three barriers with an x. One is in the Lagoon, one is at the Beach, one at the Facility Entrance. You can place dynamite here to blow the barrier up and you can walk through.