You will need to add instructions for the user and write a validation script that checks if the 'day of the week' selected is a correct date or not.
You can extract the 'day of the week' from the number value for the date by using the format string for the day of the week in the "Num2Date()' funciton format option.
// returns the day of the week 1 - 7 day of the week, Sunday = 1
// returns the abreviated day of week - 3 character value
// returns full day of the week