It's unclear to me what exactly you're trying to accomplish or whether your dispute is in litigation. That said, if you're in litigation, and if you have a friendly witness whom you need not compel / subpoena to testify:
1. In a deposition, it's not uncommon to have an out-of-state witness testify via telephone conference or video conference.
2. At trial, a Washington State superior court has discretion to allow a witness to testify "by contemporaneous transmission from a different location." However, before the court would allow such testimony, the proponent of the testimony must demonstrate "good cause" and "compelling circumstances." See Civil Rule 43, which is available online.
Hope that helps.