I would urge you to change the datatype of your date field FROM string TO date in the first place. You'll avoid all these problems in the future.
As for dates already in your system as text fields, you can do this:
dtmNewDate = DateSerial(Right(strOldDate, 2), Left(strOldate, 2), _
Mid(strOldate, 3, 2))
Michigan Dept. of Environmental Quality, Air Quality Division