On Windows 2012 R2, you can't install Visual Studio or SDK. You can use powershell to register assemblies into GAC. It didn't need any special installation for me.
Set-location "C:\Temp"
[System.Reflection.Assembly]::Load("System.EnterpriseServices, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a")
$publish = New-Object System.EnterpriseServices.Internal.Publish
$publish.GacInstall("C:\Temp\myGacLibrary.dll")
If you need to get the name and PublicKeyToken see this question.