You can launch them (The daemons) from Eclipse itself -- there must be a launch target provided in 0.21 if am right, OR you can build a fresh tar using `ant tar` target.
Schedulers are also pluggable in Hadoop, so you can develop one without needing to edit Hadoop's sources. Check contrib/ for the capacity/fair schedulers, for example. -- Harsh J www.harshj.com
