WARNING: This gist was created in 2013 and targets the legacy GOPATH mode. If you're reading this in 2021 or later, you're likely better served by reading https://tip.golang.org/cmd/go/#hdr-Configuration_for_downloading_non_public_code and https://golang.org/ref/mod#private-modules.
$ ssh -A vm
$ git config --global url."git@github.com:".insteadOf "https://github.com/"
$ cat ~/.gitconfig
[url "git@github.com:"]
insteadOf = https://github.com/
$ go get github.com/private/repo && echo Success!
Success!