You can just use the regular way of setting up a project. So Add site. Under Project Type you can select "General PHP / Laravel" and set the Web Directory to "/public". After that you can choose the correct repository and it should be up and running ;)
You of course need to make sure all other dependencies are available and all config is set!
I just installed it in less than a minute on this subdomain: http://slim.markdownmail.com/