Get the piece in the key you want it played in in a Noteworthy file. Click on "Tools" in the menu bar then "Transpose Staff..." in the drop down menu. Select either 7 or -5 as the number of semitones to transpose, whichever brings it into the soprano range. Leave "Update staff play back transposition" checked and it will play back in the original key but will look like the fingering for a soprano/tenor.