Before: git@github.com:k78ma/quartz.git

With SSH config aliases:

git@github-k78ma:k78ma/quartz.git
git@github-uwtron16:uwtron16/repo.git

So basically just replace github.com with github-k78ma

Clone with alias:

git clone git@github-k78ma:k78ma/quartz.git
git clone git@github-uwtron16:uwtron16/some-repo.git