You can simply walk up to the pass from the Routeburn Track and return the same way (5 hrs return), but a nicer option is to walk the loop via the Rockburn and Lake Sylvan. Takes about 8 to 9 hours on the whole. Loop can be walked clockwise or anticlockwise – we’ve often had two groups walking opposite directions. Good side-trip from the pass to elevation 1290.
Source: Nate Anderson