Have you seem the format string that can be passed?
http://msdn.microsoft.com/en-us/library/ms905235.aspxint GetDateFormat(
LCID Locale,
DWORD dwFlags,
CONST SYSTEMTIME* lpDate,
LPCTSTR lpFormat, <--------------- format string
LPTSTR lpDateStr,
int cchDate
);
lpFormat
[in] Pointer to a format picture string to use to form the date string. If lpFormat is NULL, the function uses the date format of the specified locale.
Use the following elements to construct a format picture string. If you use spaces to separate the elements in the format string, these spaces will appear in the same location in the output string. The letters must be in uppercase or lowercase as shown in the table (for example, "MM" not "mm"). Characters in the format string that are enclosed in single quotation marks will appear in the same location and unchanged in the output string.