Sounds like a fun trip. The Harrison Pass trail hasn't been maintained for years and in many places it is hard, if not impossible to find including where it takes off the trail to Lk Reflection. The top is steep and can be ugly if frozen. Someone else mentioned Lucy and Milly's foot passes which are similar and go to the same place.
Another possibility, and shorter xcountry route is via Vidette Lakes, over Dearhorn Saddle then a short descent and over the top part of Harrison Pass. It's through beautiful, seldom traveled country but there is some talus hopping.
Have a good trip.
