Download Windows ADK 8.1 http://www.microsoft.com/en-us/download/details.aspx?id=39982
Uncheck everything except Windows Performance Toolkit when installing.
Navigate to: C:\Program Files (x86)\Windows Kits\8.1\Windows Performance Toolkit\gpuview
Replace log.cmd with the contents from here: http://pastebin.com/jEWDMbhz
(This just adds the TRACE_VR lines with the guid we use for tracking events in SteamVR).
Open a command prompt at this location with Admin privileges.
Run 'log' to start capturing.
Run 'log' again to stop capturing (followed by a rather lengthy merge process).
Run 'gpuview' and select merged.etl to view.