From Agnes Lake attain the saddle between Mount Mahler and Mount Richthofen. From there contour along Richthofen's western flank until you reach Richthofen's southern ridge. It is not necessary to climb directly up to the ridge. This should all be class two hiking over talus.
When you attain the ridge head south for Tepee. The first thing you come to on the ridge is a 15 ft gendarme requiring several class four moves to get over it. This is very exposed so on the way to Tepee I chose to drop elevation on the east side of the ridge and bypass it. On the way back I dropped down the west side to bypass it. Both of my detours involved some class-4 moves, but they weren't exposed. Pick your poison.
When you regain the ridge try to stay as close to the ridge-proper as possible. As you progress most of the scramble should be a class three but you'll occasionally have to bust out a class four move (or at least I did). I suppose that if you had flawless route-finding skills you could keep the whole traverse a class 3. How Gerry Roach called it a class-2, talus hike is beyond me (per his RMNP guide). Continue along the ridge until you hit the headwall that makes up the summit block. Follow a talus gully down and around the west side of the summit block. You should pass a cairn so that you know you're on the right track. Descend another twenty feet past the cairn and then ascend the talus gully back up to the base of the summit block.
The easiest way to get on top of the summit block is to scramble up its southeast side.
Return the way you came.
No special gear is required if you hike late enough in the season to avoid the snow above Agnes Lake. If it's early in the season and ice axe would greatly speed the approach as climbing up snow would be much faster and easier than the talus and scree you'll encounter when the snow is gone.
If you're planning on avoiding the snow I strongly recommend a pair of trekking poles. These make the talus/scree slug a lot easier.