I needed to be able to install an old version of a package from NuGet. I couldn’t do it directly via ‘Manage NuGet Packages’, but it turns out it can be done via the Package Manager Console.

1. Open up the console via View | Other Windows | Package Manager Console
2. Use the command
   Install-Package [package name] -Version [package version]
   to install the version you want

References
How to install an older version of package via NuGet?
How to Install a Specific Version of a Package with Nuget
Package Manager Console Powershell Reference