Just installed 2010 Express Edition and I cannot see Preprocess t4 template as an option. Is it not supported in 2010 Express?
Unfortunately the item templates got a little misconfigured in our setup program for VS Express editions and are not in the right place on disk, so don't show up in the Add New Item dialog.
In VS 2010 Express Editions, we do support T4 templates of both regular and preprocessed kinds, however you'll have to set them up yourself. If you add a regular text file, then rename its extension to '.tt", it should automatically get the regular T4 custom tool set up in the property grid for the file.
For preprocessed templates, you should set the custom tool manually to 'TextTemplatingFilePreprocessor'.
The simplest test is:
In your Solution, Add New Item... look for Text Template item. If it's there, then chances are that VS 2010 Express supports T4 natively.
Take a look here for more info:
来源：https://stackoverflow.com/questions/3309551/does-vs-2010-express-edition-support-t4-preprocessed-templates