I assume that you are using AutoCAD 2000.
Although this would not be my first choice, you can change the lineweights. You can do this at the layer level, or by selecting individual entities. Then, when you plot, uncheck the 'Plot with plot styles' option and check the 'Plot object lineweights' option. These options are located in the Plot Options section of the Plot Settings tab.
A better choice would be to plot in Grayscale. You will have to make sure that your object entities are darker (black/white, blue, red) and your dimensions, centerlines, and hidden lines are lighter (yellow, green ...). Then, just load the Grayscale plotstyle and print. This automatically lightens/darkens your entities based on layer color. I have come across another user that did not have this plot style. If this is the case, let me know and I will send it to you.
Hope this helps! DimensionalSolutions@Core.com
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