Our books gave us varying altitudes at the summit, from 15,200 to 15,500. We're sticking with 15,380. Anyway, from the top of the TeleferiQo (around 13,200 - don't quote me), there is a very straightforward trail. The entire hike is quite scenic, surrounded by lush grasses and unique flora as you ascend a bit higher. The well-marked trail essentially follows a ridge for an hour or so until you reach a sand and scree area. Head past the sand and scree field to the right, where you will ascend, then eventually cross back over left. There are some footprints and faint trails through here.
You'll eventually reach the base of the summit which involves a class 2 (and class 3 if you choose) scramble towards the summit. We reached the summit in just over two hours, stayed for about 30 minutes on the whiteout on top, then began to ascend as the throngs began to arrive. For a quick descent, glissade down that sand and scree field.
I would definitely recommend this hike, either to acclimatize, or just to get away from the chaos that can be Quito. We were in the city for two days, which I think helped us move at a decent pace up Rucu because we were a bit more acclimatized -- wouldn't recommend doing this if you've just arrived. We definitely felt the altitude once we started climbing.
We heard of a mugging on the route a few days before we went up, so, don't bring loads of cash, etc. We felt totally safe, however. Email me [via the Who's Who page link at the top of the report] if you need any beta.