Just run bin/rebuild-mac.script path/to/an/existing/dir/where/to/clone/loom/sources
You may need to update the value of the org.gradle.java.home property in the gradle.properties file to point to your local build of the Loom JDK.
To run the VT-Friendly Tomcat demo, you'll have to build my Tomcat fork. To build it first run the deploy, and then the embed Ant targets. Next, install the generated tomcat-embed-* files to your local maven repo using the install-files.sh script available in my fork.
Before running the Spring Boot demo app, make sure you have the httpbin docker image running locally.