How to use fixed-width fonts such as courier in R

Hi,
  I am trying to use Arial bold for labelling (font.lab =2), and use
the fixed-width Courier bold for axis. I will export the plot to .ps
format. I have been trying to use font.axis = 11, but that doesn't work
when I exported the plot to a .ps file.

  I have been trying hard to read the help page of "postscript" these few
days, but didn't get the courier font yet.  Can you please help me
figure out how I should use "postscript"? Thanks!

Best

Sean