The package that this post is talking about is available in Package Control directly right now, so it should be enough to just select Package Control: Install Package from the command palette and then select ActualVim from the package list and you’re good to go.
If a Sublime package exists in a GitHub or BitBucket repository but is not available in Package Control, the easiest way to get it installed would be to select Package Control: Add Repository from the command palette. In the input area at the bottom of the window, paste in the full URL of the repository (https:// and all), and hit enter.
Once you do that, the package will be listed in the package list as if it was naturally there.
The worst case scenario is a Sublime package that’s not hosted on GitHub or BitBucket. In that case you need to take manual steps.
That generally requires you to go into the Packages folder (available via Preferences > Browse Packages... in Sublime) in a command prompt or terminal and manually do a git clone repository-url type operation. It’s best to do this while Sublime isn’t running so that it doesn’t try to load the package before the operation is complete.
This can be more complicated, and things aren’t automatically updated for you, so I would personally consider this the Path of Last Resort
, all else being equal. In particular, it requires you to be quite familiar with the command line in general and git in particular.