We only made it to bump 3, and that's because we ran out of time. Highly recommended hike/scramble. I would love to do the entire circuit, although it apparently involves a little bit of exposure in a couple of places. Looking at the terrain I can believe it but the allure of a horseshoe traverse is very strong.
The route beyond Whistlers summit is obvious - descending to a large col - and the ascent to the bumps isn't quite as steep as it looks. Be warned that the ascent up over the bumps is on loose shale/scree, and it can be a bit soft and muddy. Ascending the first bump is easy and involves taking a trail along the northern flank of the bump. You reach another small col and the route continues steeply up the ridgeline before you but it's really not as bad as it looks - 2 of our group turned around at this point. Bump 2 is only a short distance further and bump 3 another couple of hundred metres or so beyond that. Sadly, in order to make the last tram down, we had to turn around here. Getting to bump 4 would have taken only another 10 minutes each way. So close...
On a clear day you can easily see Mt Robson - alas today was cloudy, so our views were limited to nearby spectacular, craggy peaks and down into the valley. It was cold and very, very windy. At times we had to brace ourselves so we would not be knocked over. Placing a hiking pole was difficult as the wind pushed it to one side (usually where I was about to step...).
Note that you have to re-ascend to Whistlers summit on the return which adds almost 200 m before descending to the tramway station - the elevation gain in this report includes that whereas the top-level trip description does not.
Great hike - we'll be back!