You must have root and es file explorer
First of all download and put flash_image and recovery.img in sdcard/
Also download terminal emulator from play store.
Using es file explorer long press on recovery.img go to properties and select show checksum . Tick md5 and select calculate. This should give you a mix of numbers and characters. Compare it to the md5 sum given in the thread it should match exactly. If not download again and try.
Open terminal emulator and type su and press enter. The $ should change into # .
Now copy paste these lines as is.
# mount -o remount,rw -t yaffs2 /dev/block/mtdblock1 /system
# cat /sdcard/flash_image> /system/bin/flash_image
# chmod 755 /system/bin/flash_image
# mv /system/etc/install-recovery.sh /system/etc/install-recovery.sh.bak
# mount -o remount,ro -t yaffs2 /dev/block/mtdblock1 /system
# flash_image recovery /sdcard/recovery.img
# reboot recovery
If you get file not found error ignore it and continue.