Lady Macdonald's southeast ridge is a route that has grown in popularity in recent years thanks to it's proximity to Canmore, alpine feel, and wonderful views. The Rockies Central Guidebook has the best images and descriptions of this specific climb. For trad climbers looking to get more into the alpine, this is a excellent place to test skills. The comparatively easy technical grade and simplistic route finding make it very straightforward. But there is plenty of loose rock and tricky ridge movement to keep you on your toes.
This route starts in the Cougar Creek parking lot. This is the same lot used for Cougar Creek and Lady Mac. Proceed up the creek, moving about 30 to 40 minutes up the trail past the closer sport crags. Just past Cosmology Crag, but before Canadian Forks Crag, is a small cairn that veers steeply up the hill to the left. From here the climb is a grind up steep and unconsolidated goat paths. The popularity of the route has been improving the trail. Eventually you will reach a first band. Take the solid rock up the face here and gain a slight ridge. This leads you back to a big scree bash heading upward and upward.
Eventually you'll reach the first technical climbing pitch. While steep, the climbing is juggy protects better than the rest of the pitches. From here the route is a pretty easy progression onto the ridge and along some beautiful and narrow ridge climbing. The ridge gives way at a small gendarme, forcing a descent to the east of the ridge and taking a slab pitch up it's back on the ridge. Easy walking takes you to the final section of fifth class climbing, and you top out just beyond the main path to the false summit of Lady Mac.
For images and a detailed technical description of this route, refer to the Rockies Central Guide by David P. Jones.