Howto downgrade a MacBook Pro from Lion to Snow Leopard

Question

Preliminary:
- another Mac running Snow Leopard 10.6.8
- the Snow Leopard 10.6.3 Retail Install DVD
- the Mac OS X 10.6.8 Update Combo v1.1 (http://support.apple.com/kb/DL1399)
- Carbon Copy Cloner (http://bombich.com/)
- 8GB USB stick
### Preparing a USB-Stick with a patched Snow Leopard 10.6.3 Install ###
- Create an DVD/CD-Master image of the 10.6.3 Retail Install DVD with Disk Utility
- Eject the 10.6.3 Retail Install DVD
- Mount the new CDR image in a Terminal
# hdiutil attach /Path/to/MacOSX-10.6.3-Install.cdr -readwrite
- Change the current folder to the CDR image
# cd /Volumes/Mac\ OS\ X\ Install\ DVD/
- Double check that you are on the CDR image
# pwd
- Backup the Kernel
# mv ./mach_kernel ./mach_kernel-10.6.3
- Copy the new 10.6.8 Kernel from the Snow Leopard HD to the CDR image
# sudo cp -pv /Volumes/SnowLeo-HD/mach_kernel ./
- Copy the 10.6.8 Kernel Extensions from the Snow Leopard HD to the CDR image
# sudo cp -Rpv /Volumes/SnowLeo-HD/System/Library/Extensions/* ./System/Library/Extensions/
- Delete all Kext Caches on the CDR image
# sudo rm -rf ./System/Library/Caches/com.apple.*
# sudo rm -f ./System/Library/Extensions.mkext
- edit the Boot.plist on the CDR image
# sudo nano ./Library/Preferences/SystemConfiguration/com.apple.Boot.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Kernel Flags</key>
    <string>-v -f -x</string>
</dict>
</plist>
# cd
- Now copy the content of the CDR image to the USB-Stick using Carbon Copy Cloner
### Snow Leopard Installation on MacBook Pro 8,2 ###
- Boot your MacBook Pro from the USB-Stick
- Install Snow Leopard
- Reboot again from the USB-Stick
- Select your language
- Open a Terminal and type
# cd /
- Find your new MacBook SnowLeo-HD        
# df -h
- Copy the 10.6.8 Kernel    
# cp -pv  ./mach_kernel /Volumes/MacBook_SnowLeo-HD/
- Copy the 10.6.8 Kernel Extensions    
# cp -Rpv ./System/Library/Extensions/* /Volumes/MacBook_SnowLeo-HD/System/Library/Extensions/
- Exit Terminal
- Repair permissions on your new MacBook SnowLeo-HD with Disk Utility
- Quit Installer
- Now boot from your new MacBook SnowLeo-HD in Secure Mode (hold down Shift while booting)
- Repair permissions on your new MacBook SnowLeo-HD with Disk Utility
- Update the Extensions Cache in a Terminal
# sudo kextcache -e --local-root --system-cache (just ignore all warnings about invalid kexts)
- Install the 10.6.8 Combo Update
- Reboot

Answer 1

Holy Moly!
Your'e answer is really for those kids with no experience in a terminal.
The command line is only for pro users and should no be used by any DAU. Therefore no problem at all with "rm -rf" if you have changed into the correct directory first.
One suggetion is adding these lines to your "~/.profile"
TERM=xterm-color
# colors for misc things
export TERM=xterm-color
export GREP_OPTIONS='--color=auto' GREP_COLOR='1;32'
export CLICOLOR=1
# Set colors
export LS_COLORS='di=1;36:fi=0:ln=4;34:pi=5:so=4;5:bd=5:cd=5:or=4;91:mi=4;92:ex=35:*.r b=90'
alias rm="rm -i"
alias cp="cp -i"
PS1="(\u) \[\033[01;31m\]\h\[\033[01;34m\] [\w]# \[\033[00m\]"
Than do a
# source .profile
at the terminal prompt in order to active the settings immediatelly.
Now the "rm" command will always ask before deleting any file or folder.
Unfortunately if you like to delete a folder containing other folders with several files inside you will go mad!
One possible intermediate solution is
# unalias rm; rm -rf ./System/Library/Caches/com.apple.*; alias rm="rm -i"
But as mentioned before, if you have "sweaty fingers" while typing in Unix commands you should better stay away from the terminal.