ok, well if anyone is still interested, it turns out the the line types seem to inextricably linked to the color type, and are different for each terminal type. I recommend doing this once:
and saving the "test-ref" file as a reference for future use when you want to know what your lines are going to look like for a given type.
set size 1.0, 0.6
set term postscript portrait enhanced color lw 1 "Helvetica" 14
set output "test-ref.ps"
set terminal x11
set size 1,1
For the record though, I really think this is a cumbersome way of doing it. Perhaps there could be one command "lt" for dashes, dots, etc, and another one "lc" for line color with a few numbered options (i.e. 1-blue, 2-red, etc) standardized across the terminals. I think that would make it a lot easier, though I don't really know how to do this myself (and I do appreciate the hard work of the people who make gnuplot in the first place, I just think this change would make more people want to use it)