Install busybox to Android

1. Remount the /system file system
adb shell
su
mount -o rw,remount -t yaffs2 /dev/block/mtdblock3 /system
exit

2. Copy busybox to /data/local/
adb push busybox /data/local
adb shell

3. Create /system/xbin folder
/data/local/busybox mkdir /system/xbin

4. Install busybox
cd /data/local
chmod busybox 755
/data/local/busybox cp /data/local/busybox /system/xbin/busybox
cd /system/xbin
chmod busybox 755
./busybox --install -s /system/xbin
rm /data/local/busybox