From Lightning Lake in Manning Park, the route begins at the eastern corner of the lake, at the signpost saying "Frosty". This is the "Frosty Mountain Trail", take this trail to the east peak of Frosty Mountain, where there's another signpost saying "Elev 2408m". The FKT route is signpost to signpost to signpost. There is only one intersecting trail along the route, right at the ridge. Once gaining the rocky ridge you can see your target, Frosty Mountain, to the right. Do not take the left trail which heads downhill and away from Frosty towards an area called Windy Joe. All in all this route is very straightforward.
*also recognized as a Strava segment called "Frosty Up Down"*
"Frosty Mountain in Manning Provincial Park is a challenging hike that takes you into the alpine to a viewpoint on the first peak that provides a spectacular view of surrounding Coastal & Cascade Mountain ranges. The trail steadily ascends and some scrambling over loose rocks is required before reaching the top but the views on a clear day are some of the best in the park."