You might be asking why you would ever need the Industry Nine Pawl Spring Set. A curious person should ask. Maybe you're just too damn strong and have broken the pawl springs. Maybe you like to bathe your hubs in a mud bath and have been known to use a high-pressure hose to clean out your bike parts. Maybe you lost one when you were doing your regular hub service. We don't need to know -- the parts are here if you need them.
In terms of hub service, I-9 has posted a PDF on their website's "support" page. The whole process is there, step-by-step, with photos and drawings.