From the west side of Guanella Pass, start your journey towards Squaretop Lakes on the South Park Trail
. It is ~2 miles to the lakes at the base of Squaretop Mountain
and the Lakes themselves. When I went, the trail was clearly defined through the willows, however, I have read different trip reports of people having some troubles depending on the time of year.
Once at the lakes, make your way up the east-facing grassy slopes of Squaretop. I didn't see a real trail; I just followed the path of least resistance to the large, broad summit of Squaretop. This is not to say there is not a trail, I just didn't see one as I was descending.