Here's a little script I use from within my empeg-kernel-source directory:

#!/bin/sh
export PATH="/usr/local/empeg-toolchain/bin:$PATH"
if [ -f .config ]; then
exec make zImage
fi
make mrproper && make oldconfig && make dep && make clean && make -j3 zImage

To build a kernel, I just to ./buildit (that's my name for the script) instead of typing 'make'.