The wiki should be updated on this.
The problem with this method is all of the kexts in the actually booted OS are seen as not loaded
by OSX and the system always wants to rebuild the boot cache when restarting or shutting down.

Only 3 files are needed on the boot drive: 1) Library/Preferences/SystemConfiguration/com.Apple.boot.plist
2) System/Library/Extensions.mkext
3) mach_kernel
This way when you add kexts you add them as you normally would and only have to copy a refreshed Extensions.mkext to the boot drive
after adding or removing kexts.

Also if you multiboot many OS's on different hard drives often when doing a warm reboot hard drives can be ordered differently so it's much
better to boot your Raid array by UUID.

You get the UUID "Unique ID" of your Raid array by running- "diskutil listraid" in terminal
then you simply add: boot-uuid=XXXXXXXXXXXXXXXXXXXXXXXXXXX to the com.Apple.boot.plist
as a Kernel Flag instead of rd=disk2

Also to make it cleaner you should create an entry using uuid of boot part in /etc/fstab to prevent
the boot drive from automounting. That way the 1GB boot partition won't show up on your desktop.
If you ever need access to the partition you just mount it using diskutility. Just add the line
UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx none hfs rw,noauto 0 0
to etc/fstab of the RAID array.
Of course in above examples where you see xxxxxxxxxxxxx you would insert your own UUID.