If you've ever tried to build a deployment image directly from individual iLife packages (onto say a sparse image), then you've no doubt seen this error message:

installer: Error - You are attempting an unsupported installation. If you wish to install an individual 
application, please use the iLife installer and select the Custom button.

Bummer. Well, luckily there's a really simple workaround:

touch /tmp/com.apple.mpkg.iLife

and then run installer again. :)