See also: Sufia source.
To replicate the base of this project, follow the basic application instructions, except using relative path instead of a version number for the Sufia dependency.
Get Sufia source and dependencies
git clone git@github.com:projecthydra/sufia.git
cd sufia
bundle install
cd ..
rails new sufiatest
cd sufiatest
gem 'sufia', path: '../sufia'
Just follow the rest of the recommended Sufia setup, including running the generators, migrations, and Jetty/Redis startup. Once everything is running, you can modify most of the relevant code in Sufia and the application without restarting any of the pieces.