Advanced modification of preferences is achieved by the defaults command in the Terminal application.
In setting a preference you specify a descriptive key and it's given value with the following syntax:
defaults write net.glencode.Particulars key value
You can reset a key to its default value using:
defaults delete net.glencode.Particulars key
Or you can read the value of a key using:
defaults read net.glencode.Particulars key
When setting preferences for the Today Extension (Widget) use net.glencode.Particulars.Widget instead of net.glencode.Particulars.