How can I embed one syntax highlighting language into another one?

It is possible to include one syntax highlighting into another one, however most of the currently deployed syntax highlighting scripts are not prepared to be included into another syntax script. You can however create your own custom script to define your own regions, which will be highlighted with a different language. See the wiki for a comprehensive solution: http://vim.wikia.com/wiki/Different_syntax_highlighting_within_regions_of_a_file