This worked. Installing Final Cut Pro 7 on OSX Lion

Installing from the command line will get around the "PowerPC applications are no longer supported." install failure message.

$ sudo installer -package /Volumes/Final\ Cut\ Studio/Installer/FinalCutStudio.mpkg -target /

and then to install Live Media Discs

$ sudo installer -package /Volumes/LiveType\ Media\ 1/Installer/LiveTypeMedia1.mpkg -target /

$ sudo installer -package /Volumes/LiveType\ Media\ 2/Installer/LiveTypeMedia2.mpkg -target /