Hi I have been successfully using the magic lantern software on a EOS M camera - using the microphone as a cable release port. Will I be able to do the same thing ie connect a cable release to an M3 if I buy one? Regards Flash
The EOS-M3 isn't supported. Development is in the very early stages so there's no knowing when or if it will be working.
http://magiclantern.fm/forum/index.php?topic=14990.msg169808#msg169808
However, there are several ways you can trigger the camera remotely including an infrared remote (http://support-hk.canon-asia.com/contents/HK/EN/8202260500.html) and phone via wifi (http://support-hk.canon-asia.com/contents/HK/EN/8202462600.html).
I can confirm that USB_Remote (http://chdk.wikia.com/wiki/USB_Remote) works.