I just tried it and although the setting is available, there was no effect on the displayed line types regardless of the ltscale and psltscale settings. I don't know what this does unless it changes the ltscale of the viewport boundary itself.
I noticed the same thing... nothing.
It appears that only changes the ltscale (or CELTSCALE) of the viewport linework. *sigh*
Give it a shot... type CELTSCALE, then change it to, say, 0.25, then create a viewport. Click on the new viewport and check out the ltscale of it. It'll show up as 0.25.