This could be done, but it would be tricky. You can use the Ranking item type in MediaLab for the rankings, no problem. You can track the rankings of the items in a responses.xls file (see Advanced Features). You can then create some new variables with conditionals that determine which variables will be picked and then present those in your subsequent items. Not sure if you have used the Advanced Features of MediaLab before. If so, check this out and see if it helps:

http://support.empirisoft.com/showthread.php?p=3229

If not, take a look at the section on advanced features in the user's guide and see if it starts to make sense. There is a good sample that illustrates what you can do with it.

Hope that helps,
Blair