1. Compile a zImage
    cd {your source}/
    edit make_kernel.sh change i9502 to i9500 or i959 which should be your device.
    ./make_kernel.sh
2. To make a initramfs cpio image
    cp -a {your device}/boot-ramdisk {your place}/
    cd {your source}/
    find -name 'zImage' -exec cp -av {} {your place}/ \;
    find -name '*.ko' -exec cp -av {} {your place}/boot-ramdisk/lib/modules/ \;
    chmod -R g-w {your place}/boot-ramdisk/*
    cd {your place}/boot-ramdisk/
    find | cpio -H newc -o --quiet --file={your place}/boot-initramfs.cpio
    cd {your place}
    gzip -9 boot-initramfs.cpio
3. Make a boot.img
    {correct place}/mkbootimg --kernel {your place}/zImage --ramdisk {your place}/boot-initramfs.cpio.gz --board universal5410 --base 0x10000000 --pagesize 2048 --ramdiskaddr 0x11000000 -o {your place}/boot.img
    Then the output is {your place}/boot.img