Pat's on track with this. (As usual for Pat.)
Look up Access help on COMMAND LINE actions. I think it is /X macroname that will do what you want.
First, build a macro that performs the TransferSpreadSheet action that is required for your external update.
Second, include a Quit action at the end of the macro. Do not attempt to start the next step until the macro, once started, correctly exits from the application. You are NOT done until this is true.
Third, create an extra Icon that points directly to the .MDB file, created as a shortcut on your desktop.
Fourth, open the Icon to see its properties. (This is just a right-click operation, click on "Properties").
Fifth, edit the "Target" line on the "Shortcut" tab-page to include "/X macroname" where you supply the correct name of the macro. HINT: Keep the name simple.
Sixth, get into the Windows task scheduler. Schedule the icon to run at your desired time/frequency.