Rooting
get "adb" tool from android homepage.
connect ADP1 (android phone) via USB to the machine on which "adb" tool is installed.
Make sure that, in *Settings-->Applications-->Development* section of android phone *USB debugging* option is enabled.
$adb shell gets you a command prompt '#'
#mount -o remount,rw -t yaffs2 /dev/block/mtdblock3 /system
#cd /system/bin; cat sh > su; chmod 4755 su; exit