Cross Linux From Scratch (CLFS) is a project that provides you with step-by-step instructions for building your own customized Linux system entirely from source. This is a multi-architecture version of Linux From Scratch that is cross-compiled. It currently supports Alpha, MIPS, PowerPC, Sparc, x86, and x86_64.
More Information about CLFS
For packages not covered in CLFS, you can look at our Community Driven Beyond Linux from Scratch Wiki. http://cblfs.cross-lfs.org