The Device Tree Compiler (DTC) project is hosted at OzLabs. The website seems to be unavailable at the moment, but the git repository at git://ozlabs.org/srv/projects/dtc/dtc.git seems to work.
Cross-building the tools works fine. This is what I did:
$ export CC=ppu-gcc $ make
This will create the dtc and ftdump tools which can then be copied to the target machine.