AutoSave was removed with xl2002. But if you have an old version of
autosave.xla (it came with earlier versions of excel), it'll still work in the
newer versions (xl2002+).
If you don't have a copy available...
Another option would be to dump autosave and use Jan Karel Pieterse's addin
(works in any version) called AutoSafe (note spelling).
It doesn't overwrite the existing workbook when it saves. It saves to a user
selectable folder. And when it's done, it either deletes these backups (or puts
them in the recycle bin). And the user can always restore the backups from the
recycle bin.
http://www.jkp-ads.com/Download.htm
(look for AutoSafe.zip, not autosafeVBE.zip, for your purposes.)