You need to have few basic packages installed in your system (perl, cpio, gzip and zip), which most already do. I've added an adb push boot.img to phone function which is experimental but working (you need to have adb shell root access and your sdcard needs to be mounted).
Place the boot.img you want to edit inside the bootkitchen folder. Run the script with:
./start.shSelect 1 to decompress the ramdisk and kernel from the boot.img
Select 2 to create a new boot.img from kernel and ramdisk
Select 3 to create a update.zip to flash with ClockWorkMod
Select 4 to adb push boot.img to phone (experimental)
Replace the zImage or modify the ramdisk. All made easy.
Useful information on splitting boot.img for those who are more interested.