Manual install
Place state-card-custom-ui.html and state-card-custom-ui.html.gz in ~/.homeassistant/www/custom_ui/ dir to install the main code.
Additionally on HA 0.59 and later place state-card-custom-ui-es5.html and state-card-custom-ui-es5.html.gz in ~/.homeassistant/www/custom_ui/ dir to install the es5 version.
(HA 0.52 and earlier only) Place ha-panel-custom-ui.html and ha-panel-custom-ui.html.gz in ~/.homeassistant/panels/ dir to install CustomUI configuration panel.