Options to use gcc 4.7 or 4.8 cross-compiler for arm

First, thank you for providing such a quality tool to help a noob like me building a kernel.
However, during compiling a kernel for my G3, I ran into a "vmlinux.o mismatch" error, which seems to caused by the gcc 4.8 arm cross-compiler. I used the 4.7 and it ran perfectly. So if you can, please add the option to use either 4.7 or 4.8.