Follow these steps to add an automatically loading LISP routine to your ACAD STARTUP.

1. Save the LISP file with lsp extension to your C drive in this directory C:\Documents and  Settings\username\Application Data\Autodesk\..your AutoCAD version here..XX\RXX.0\enu\lisp routines folder.
2. Open AutoCad and type “APPLOAD” in the Command line.
3. When the dialogue box pops up, click on
the “contents…” button in the bottom right hand corner (“Startup suite”).
4. In the Startup Suite dialogue box, select the “Add…” button.
5. Browse for your LISP file with .lsp extension that you have saved before.
6. Click Add once you find your lisp file.
7. Close all dialogue boxes and you are done.

The next time you open AutoCAD the lisp routine will automatically load without any command invoke.