This actually works, at least in some cases.
PROCEDURE TwoByFourWallLow;
VAR
h :HANDLE;
boo :BOOLEAN;
BEGIN
NameClass('plan-walls low');
CallTool(-208);
h := FSActLayer;
boo := SetWallHeights(h,48,48);
boo := SetWallThickness(h,3.5);
END;
RUN(TwoByFourWallLow);
What's not working is the script only sets the first wall segment created. The width and height of the second segment reverts to whatever the tool preference was befor. I would think VectorScript capable of setting the Wall Attributes Preferences.