First you will have to know what your drawing units are. Type units from the command line.

If for example, one drawing unit happened to be 1 inch, then you would want to set up the plot scale for 12 drawing units.

Do not let the application allow the plot to "Fit to page". Unselect that option.

You will also have to tell the plot function the paper size that you require.

There are other ways to accomplish this. Set the limits to the paper size and plot to the limits. Or use a scale of 1 inch equals 1 foot.

Without setting up the plot, you will get unexpected results. Preview the plot first.

Take the file down to a print shop. They can save you time and trouble.

This is all correct but you might still have to adjust the scale if the printer or plotter tries to fit the print to the paper margins. You'll have to do a test print to check this.