I use EDTracker (EDT) though the wired version but I guess it should be mostly the same. In your Opentrack DCS profile set the output as 'freetrack 2.0 Enhanced' or similar and in the settings for that output select 'Use TrackIR, hide FreeTrack'. In DCS, the EDT should show up as a controller but you don't need it because the default TrackIR settings, as per Phantom453's image, will be working with EDT so make sure and clear all the EDT bindings.
Hope that helps.