Currently, you would only be able to complete this task using MediaLab. MediaLab has the ability to harness much more power using excel - DirectRT currently cannot.

By using logical IF statements within excel, you should be able to create a system in which the requirements you've noted can be met. See the following link for more information:
http://www.empirisoft.com/medialab/h...d_features.htm

Let me know if you need more help creating an input file with this functionality.

Also - it should be noted that DirectRT 2010 will have the ability to harness excel in the same way that MediaLab can before its Fall release.