It's a little tricky to find, but go to Pioneer Square and then find 1st and Washington and park, and then walk East on Washington (around a tiny corner), which is up, and you'll find it.  You can't drive up that way cuz it's a one-way, so park and walk up.  If you are near the J&M, Last Supper, or the Central, you're right in the vacinity and you can ask anyone where the Catwalk is and they can help...or you guys can call me and I'll help you...206-459-6452.