Actually, you *cannot* add shortcuts of commands *and their options* to the Acad.pgp file; it only permits shortcuts of the commands themselves.
The simple (and effective) Visual LISP function that Joe posted works well, but would be better if placed in the AcadDoc.lsp file, instead of the Acad.lsp file (as Acad.lsp is normally loaded only once per session, while AcadDoc.lsp is loaded for each document opened).
There is also a bug since A2k <sigh, fix it Autodesk!> that might affect you. In some situations, if you select a drawing off the Most Recent Used list on the File menu, none of the code in the Acad*.lsp files will run. However, if you have a customized menu, place all this code in the menu's ..mnl file, and it *will* load.