Follow Highway 99 (Sea-to-Sky) a short distance north of Squamish to Squamish Valley Road, directly across from Alice Lake Provincial Park. Turn left on Squamish Valley Road and reset your odometer, following it for 26.5 km. It should be noted that kilometer markers along the route vary wildly and for the most part cannot be trusted - use your car's odometer instead.
Eventually the road will turn to gravel and become Squamish River Forest Service Road. Follow it for approximately 2-3 km, ignoring all side roads and passing a hydroelectric power station on the right. Cross over the bridge after the power station and drive past the High Falls Creek trailhead. 1.4 kilometers past the bridge, turn right onto an unmarked road - this is BR200. (total distance approx 28 km Highway 99)
Turn right onto BR200 and reset your odometer.
2.3 km - stay straight
6.0 km - take right (main) fork
7.9 km - take left fork
9.5 km - road becomes extremely rough, tough 4x4's only past this point