Give input to "Add Frames to Timeline Prompt"

So I've got a scene with less frames in the timeline than the pose preset I'm merging. Simple stuff:

var oContentMgr = App.getContentMgr();
oContentMgr.openFile("C:/folder/AnimationPosePreset.duf", true);

This gives me the message:

This preset contains information for frames beyond the length of your current timeline.

Would you like to add frames to the timeline in order to import the entire file?

With "Yes" and "No" (Yes is pre-highlighted)

How do I 'click' yes on this window via script?