Since my parking brake control is going on the pilot's side left panel, I found it very convenient to attached the parking brake valve to the side of my avionics tray, that sits right behind the panel there. I cut the parking brake cable to size, but still left about an extra foot until I'm installing it in the permanent panel.
I also finished all the plumbing, running a 1/8" line from the master cylinder, through the parking brake valve, back down to the bulkhead and into a "T" fitting, and attached the lines that were previously installed through the landing gear legs, down to the brakinhg calipers. I zip-tied where needing to keep it all hidden and in place. All the brake line are sheathed in a black plastic protective cover.