They are in the archive section of eDocs on Mitel Online... if you have access to that.
You will still need a physical CD of the docs though, as they require Folio Views for Windows which I have not been able to find anywhere else but the CD for many years. It will require XP or older to work out of the box, it does work for Win7 but requires some tweaking to function.
The tech handbook is a PDF document though.
