You could use a MIDIMapper with Map set to:
!End is: (`End displayAs: #fader; min: 0 max: ('count.aif' sampleFileDuration removeUnits * 1000)).
For other examples showing the syntax, check in the text file default.map, for example:
!WiiTrigger is: (`WiiTrigger displayAs: #gate; min: 0 max: 1 grid: 1).
Or check in Kyma X Revealed on page 390.