Yep unmount then open terminal and do all the previous stuff,

but how?

boot with dvd
then choose disk util
click on partition click unmount
for all partitions, when you open disk util its self explanitary
then open terminal and do all the previous

ive unmount the partions andnow?

change directory to i386 on your dvd 3- type cd /usr/standalone/i386

4 - type "dd if=./guid/boot1h of=/dev/rdiskXsY bs=512 count=1 (X is the disk number and Y is the partition number on which you installed Leo)
5 - type "dd if=./guid/boot0 of=/dev/diskX bs=400 count=1
6 - type "./startupfiletool -v /dev/diskXsY ./boot_v8"

ohhh -snipped- it the same -snipped- >DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER< what's wrong with me?

sorry guys im too silly

r you sure you are using the right disk partitions?
I am guessing that if your osx partition is first on your disk and you are using guid it will be disk0s2
to check this

in terminal write
diskutil list

ill check this

if thats the case you should write in terminal after unmounting

you must cd to the i386 folder first, then type

after each line you should get
a message that it has wrote data

he started the setup!!