How to use external toolchain with meta-sifive

Hi all,

Is it possible to import external toolchain and use it in yocto build process? Buildroot proveides external toolchain configuration and works perfectly with the preinstalled toolchain on my host to skip the lengthy pacakges building needed by cross-toolchian.
I’ve tried meta-sourcery but there are too many error that I cannot resolve and it’s also not a popular project so i doubt this way does the trick.
Any suggestion on this usage?