This is how I do it. First I add all the stops in order for one direction. Then I create a bus route relation and select the roads buses go on. I add them to the relation. I then do the other way around as another relation. Then I create a route master and add the two bus route relations to the route master.

I try to fix the cycling routes in my city. As of now they're all mapped as if they were seperate cycling paths, even though most of them are roadside lanes seperated by flimsy plastic barriers.