The essential factor here is that your printer be able to print this paper
size. If it cannot, then you won't be able to print it by any method. If it
can print the size but doesn't have a definition for it (unlikely), then
you'll have to set the card up on some other size that is defined, adjusting
the margins (and feeding the card) accordingly. If the printer can't handle
this size, then you can get Avery cardstock (or the equivalent) that has
several (preperfed) 3" x 5" cards on a sheet of Letter-sized stock.