I discuss this on page 195 of my book. CR uses the current locale for setting the date format. But it was buggy and they are supposed to fix it with a service pack (I haven't checked recently so see if they've done it, so you should download the latest SP and see what happens).

If it doesn't work, you can make the the parameter a string and use an edit mask to format it how you want ("00/00/0000" or whatever). Then use the Date() function to convert the string to a date in your record selection formula.

You can find out more tips and tricks about Crystal Reports in my book Crystal Reports Encyclopedia.