Add the following to your init file
(require 'mastodon)
(add-to-list 'load-path "path-to-modules/mastodon-future.el/lisp/")
(require 'mastodon-async)
(require 'mastodon-inspect)
(require 'mastodon-profile)
(require 'mastodon-notifications)
(define-key mastodon-mode-map (kbd "D") #'mastodon-inspect--toot)
(define-key mastodon-mode-map (kbd "U") #'mastodon-profile--get-next-author)
(define-key mastodon-mode-map (kbd "N") #'mastodon-notifications--get)
There is also an alternate toot-renderer. Note that it has NOT been fully integraeted with all time line funcitonality.
(require 'mastodon-render)