Have you already filed suit? This is a relatively easy process, once you have filed a complaint. Your lawyer should simply be able to issue a subpoena to the hosting company. Absent a valid objection, (in the form of a motion to quash) they should comply.
I am assuming that you don't have a lawyer. In this case if I were you, I would hire a lawyer to handle this issue. It's not easy to explain. If you must figure this out yourself, I would start with the Washington Civil Rules. There is a copy online, and if I recall correctly, there may be a form attached to the newly revised rule. Try courts.wa.gov for starters. I would still hire a lawyer if I were you, as there are also procedural rules to follow in addition to the basic rule.