Cross-Linux From Scratch has a huge amount of information available for both host-system and compiler setups.
The OSDev Wiki also has a ton of info and links for cross-compiling. It mentions Clang/LLVM making this easier than most.
Edit: I did read you were looking specifically for shared libs, but personally, I don't see any way around using a compiler for that unless they were already built and you were looking for a custom linker/loader design, etc.