I believe It actually doesn't get cleared until the lens gets drawn in (like manual focus and zoom positions). Therefore if you have the option to make that power saving timeout longer from Canon's settings menu, it may help a bit. Other than that, options are a bit scarce. CHDK could probably be made to do this, but current versions don't.
You can however set a script autostart at boot time and have it
- check that you booted to rec mode, end & exit alt if you aren't
- wait until the camera is likely ready to receive keypresses
- press the MF button a suitable amount of times to switch to macro mode
- exit alt mode
