[Macpartners] replace Finder with another app (under Tiger)

[Duncan Kincaid]

wish to make kiosk by replacing Finder with some other app at login.

can;t find any documentation on how to do this under Tiger.
(the old method of
 > defaults write com.apple.loginwindow Finder <path_to_replacement_app>
doesn't seem to work any more (for me). all this does under Tiger is  
set the replacement app to auto-launch.)

has anyone the secret for doing this in Tiger?