Here's a super short version how to build Cesium with perylune:
cd cesium
ln -s ../data/czml
npm install
npm start
To build release version, do:
npm run build
and then you should get the package in dist/ directory.
Upgrading to latest cesium:
npm install cesium
Note: the labels will be shown as random garbage if firefox's resistFingerprinting feature is turned on.