Printing in landscape

[Bill]

I have a stack that is smaller than an 8.5 by 11 sheet of paper
(it is 728 pixels by 636). I presently put png images which are several
thousand pixels wide by height (to get the resolution) and told to be 612 by
792 and "locked" in with the size and position panel.

I then print them with the following button:

on mouseup
  -- printMargins left,top,right,bottom
  
  set the printmargins to 0,0,0,0
  open printing with dialog
  print card from 0,0 to 612,792
  close printing

end mouseup 

This works fine except now I want to print some forms that are landscape and
putting them on with width 792 and height 612 (so they will be right side up
and not sidewise) prints only as much wide as will fit on the paper.

How in mac os x do I get the printing to come out in landscape and thus get
the whole form?

By the way this method gives me very clear 300 dot per inch printing on my
laser printer but is a little slower than ideal (takes several seconds).