I have tried
F12:: Send, {LAlt Down}{=}{LAlt Up}
which was recored by Macro creator but did not work. Also a variety of changes like !{=} , !=, and SendPlay as well.
It seems it is not possible to remap Alt + = in Onenote using Autohotkey. However, those with Ctrl shortcut can be mapped with Autohotkey though.
Do you have a solution ?
F12:: Send {LAlt Down}{=}{LAlt Up}
andF12:: Send !=
worked equally well for me. After you added the mapping to your script file did you tell autohotkey to reload it? – Glenn Stevens Jan 31 '13 at 7:48