[cc wookey as he’s the project lead and author of the most recent communication I can find]
Recently it was explained to me in https://bugs.debian.org/838779
that there is a neat way to install new repositories without using apt-key and manual fingerprint verification.
(I tested that the above commands work — in principle — with Debian jessie.)
$ gpg --no-default-keyring --keyring emdebian-toolchain-archive.gpg --import /tmp/emdebian-toolchain-archive.gpg
I can then gladly take care of updating the wiki appropriately.
Thanks a lot!