Due to my old method not supporting FileVault and the hassles some have had due to different Lion builds I've written a little app to take the stress out of installing Lion on a machine upgraded to a Core2Duo.
Step 1 - Patching the Installer
Run the patcher and select the 'Install Mac OS X Lion' app downloaded from the app store (works with any Lion build from DP4 onwards).
Step 2 - Installing Lion
Then run the Lion Installer from within Snow Leopard. After rebooting and loading the 2nd stage installer it will give you a warning about your system not being a supported mac…. Just click 'OK' and install to your chosen HDD/partition.
Step 3 - Making Lion bootable
Boot your machine with any OSX Install Disc or previous version of MacOS on any partition/external drive). Open terminal and delete the following file:-
"/Volumes/'name of your new lion partition'/System/Library/CoreServices/PlatformSupport.plist"
Step 4 - Making the Recovery Partition bootable
Mounting the recovery partition. In the terminal type 'distil list' and make a note of the 'Apple_Boot Recovery HD' partition number and the disk it's on (it will usually be partition 3 on disk 0). Then run the following command 'distil mount /dev/disk0s3' (obviously using your disk and recovery partition numbers!) Then in the terminal type 'sudo rm -rf /Volumes/Recovery\ HD/PlatformSupport.plist'
Now you can boot Lion and also use the Lion Recovery partition