A "RuntimeTextTemplate" uses TextTemplatingFilePreprocessor to generate C# from a T4 file that can be executed anywhere to generate the text artifact (this is different from TextTemplatingFileGenerator which generate the text artifact when saving the T4 file in VS).
AFAIK TextTemplate.exe can't be redistributed (GarethJ knows) so generating text artifacts from T4 using that tool on a non-VS machine is prohibited.
Mono has their own T4 Engine which potentially could be used instead.