The only way I can think of to do this would be to manually enter the RTs from one subject as display times for another. This would be pretty easy in DirectRT as you could just copy the RT data column into the TIME column of the yoked subject's input file. You could do it with MediaLab, it's just that the ML input files are vertical whereas the data files horizontal (one row per subject). This would be a one cell at a time sort of thing. There are some ways to make that more efficient--if you want I can elaborate.