You can't, without having OneCare go to at risk status.
These links might help you by preventing the reboot -
Disable reboot after Windows Update:
http://www.wikihow.com/Disable-Automatic-Reboot-After-Windows-Update
http://4sysops.com/archives/disable-restart-after-windows-automatic-updates/
http://www.online-tech-tips.com/computer-tips/disable-restart-now/
Note that, since OneCare is at End of Life, you may simply want to uninstall OneCare, run the cleanup tool, and install Microsoft Security Essentials. Then in the AU settings in Control Panel, select
the options for AU as desired (notify only, download and install at time specified, etc.).
See this post for End of Life information for Windows Live OneCare -
http://social.microsoft.com/Forums/en-US/onecaregeneral/thread/81996436-edad-41ba-bdfc-02fc094e2ca9
Cleanup tool -
http://social.microsoft.com/forums/en-US/onecareinstallandactivate/thread/399071e2-49dc-4767-932d-d261e3965943/
official MSE download page
-steve
~ Microsoft MVP Windows Live ~ Windows Live OneCare| Live Mesh|MS Security Essentials Forums Moderator ~