How to place a cue anywhere on a ridewithgps route

One problem I have with the ride with gps route planner is placing a custom cue on the return leg of a route. In the example below, I want to place a custom cue at mile 96.9 but when I hover over the map it thinks I'm pointing to mile 29.3 because the route goes out-and-back over this section.

It turns out you can add a cue by clicking on the elevation chart. But the elevation chart is too granular. A one pixel movement of the mouse causes the insertion point to jump from one side of my target insertion point to the other.

You can zoom in on the elevation chart by clicking on one side of your insertion point and dragging to the other side. Like this...

Now the map and elevation profile zoom and you can get much finer granularity.

Click exactly where you want on the elevation chart to place your cue precisely.

When you're done, click De-select in the elevation profile.