--insecure doesn’t work because github doesn’t allow insecure connections. You’re saying you’re ok with insecure, but github says nuh-huh.
Looks like other people have made it work. I can’t vouch for these steps - the risk is your own etc.
Another approach that might work is to copy the various files and tarballs the homebrew installer is looking for to a web server on your local network. On your 10.8 Mac you would add temporary entries to your
github.com pointing to the IP address for that local web server. This way the homebrew installer would get the files it needs from your local web server instead of trying to make connections to github. Once homebrew is installed, you would:
brew install openssl
brew install curl
echo 'export PATH="/usr/local/opt/curl/bin:$PATH"' >> ~/.bash_profile
Then remove the temporary
Have never actually done this, so don’t know if it would work.