If you want PS files (e.g., to send with an electronic submission to PRB), create the PS file from the Mac by "Print"ing to a file, and then select the "Postscript" option. Note: You cannot do this by printing to the Phaser 560. I don't know why.
However, if you want an EPS file (e.g., to embed in a galley-style paper), create the EPS file directly from the Mac again by printing to a file, then selecting the "EPS" option (I haven't found much difference between the various preview options.) Note: DO NOT create a PS file on the Mac and then convert it using "ps2epsi" on the unix machines. The postscript generated from the Mac contains all sorts of weirdness which causes this not to work. Also, the Mac doesn't seem to do a very good job of putting the bounding box around the figure. So, you can either use bbfig (e.g., "bbfig temp.ps | lp") to find the best bounding box, or do it by hand.