Well, I looked at it over and over again and it seems that the variable data is stored in the Layout object list, but while you can change it directly, it will not become active unless you switch the layout... now how silly is that. The DXF code is automatically updated to the value of PSLTSCALE only when the layout is changed, so if you changed the layout directly via lisp, the PSLTSCALE will still be the other setting until you switched the layout, at which point the layout is updated to the value of PSLTSCALE which defeats the purpose all together. There may not be a simple answer, but I have not yet given up hope.