[yocto] External toolchain

[Virgilia Eigner]

Hi,
 
I am working on a image for my personal hardware.
In this case I use to prefer my own toolchain (used before in buildroot).
Now I am not sure how to proceed. 
Is it possible to include the old toolchain with a few chance setting in local.conf
Or do i have to create my own Layer? 
How should i start with, are there some examples?
 
-Yocto Version YP Core-Dizzy 1.7.2
-My own customize hardware, with different interfaces
 
 
best regards Lisa