Francois,
Thanks for the quick response. I did manage to borrow some code from the Average files process and create a modified version of the process_timefreq.m file that allows for the grouping features I want. I originally named the file "process_timefreq_pk.m" and I got a strange "context" error when I tried to run it. It works if I keep the original process_timefreq.m filename and store the file in my own personal process directory, but then the original process no longer shows up in the usual place in the drop-down menus. I wasn't successful at tracing back the source of the error. Any ideas would be appreciated.