You can have .NET compile and minify your less files on the fly for development and testing. This uses MVC4 and the excellent web optimisation tools to bundle up the required files and apply a less transform on each request. It can even minify your code in production.
You simply need to use the included Bundle transformation and virtual file reader to allow for file imports within your less.
When you change any less during development it detects the change and recompiles in on the next request
Get the source on the following gist
NB dotless doesnt yet support the latest version of bootstrap so you need to go back a version to get it working
Built using the great dotless project