Building Firefox in two stages

I have 2 GB of core and 4 GB of swap, but I still run out of memory during the standard Crux build of Firefox. I can however build it in two stages (xulrunner first and then the browser), as described in Beyond Linux From Scratch. I have now created two Pkgbuild files that allow the job to be carried out automatically, and have verified that they work for both installing and upgrading. I'd be happy to pass them on to anyone who has similar problems.