You want to fill the screen as much as possible with the area you want to print. Click on "Parallel Project" and the view you want from the Camera menu. Then go to Print Preview. Unclick "Fit to Page" and "Use Model Extents" and Scale boxes should be lit up. Enter 1 in both of them.
Only problem I've had with it is that it wants to print the entire screen so if something is real long or real wide in ratio to the other dimension, it prints out some unneeded blank pages.