When you install showanalyzer you also get installed a program called Schoolhouse.
This is a GUI to showanalyzer and lets you fine tune commercial detection.
Record some shows (one or two for each channel you want to have skipping on) and then for each one do a couple of runs through Schoolhouse.
Fine tune the detection settings in there and save the profile.
You can allocate different profiles to different channels so if the detection scheme is good for channel 7 but crap for 10 then you can set them differently. You'll probably have to get on the showanalyzer forums at
www.dragonglobal.org to figure out how to do that.