Hey Acldemac,
I just wanted to add to my post.
Although you cannot change the way the date is formatted in Method, you are able to format the way the date is printed/emailed on a report.
If you want to change the date format on reports, open the report in the Report Designer. Once open select the date field you want to format and once in the properties window, you will be able to change the way the field is formatted.
When entering information on screen in Method, you must follow the current format, you can use the date picker or just type in the format of MMM-dd-yyyy.