14.2.2 Manual

To install go-mode manually, check out the go-mode.el repository in a directory of your choice, add it to your load path and configure Emacs to automatically load it when opening a .go file:

(add-to-list 'load-path "/place/where/you/put/it/")
(autoload 'go-mode "go-mode" nil t)
(add-to-list 'auto-mode-alist '("\\.go\\'" . go-mode))

Either evaluate the statements with ‘C-x C-e’, or restart Emacs.