Suggested solution in 2007-2009: Use the Installation Wizard. The Wizard will registered the LTScale Switch for self loading in the current AutoCAD. If you have many vertical AutoCAD of the same release, use the next solution for each of them.
Alternate solution and previous releases: You need to copy the LTScale_Switch_2007.arx1 file in one of the AutoCAD search path and load it once. It will be self-loaded next time so you will never need to care about it anymore. A button is dispayed in the status bar to let you toggle from active or sleep mode or set new parameters.
<1> or LTScale_Switch_2004.arx for AutoCAD 2004-2005-2006,
or LTScale_Switch_2000.arx for AutoCAD 2000-2000i-2002