These instructions are for a SLR conversion. A Leica M240 family lens conversion for reflex focusing is just as doable.
http://www.instructables.com/id/Instamatic-lens-for-Canon-EOS-body-Kruzamatic-len/?ALLSTEPS
http://www.instructables.com/id/Instamatic-lens-for-Canon-EOS-body-Kruzamatic-len/?ALLSTEPS