I recently upgraded my G4 to a new macBook Pro 2.4Ghz. The process of migrating data from the old to the new laptop was performed using the migration wizard over firewire. I had several gigs of data, therefore the process took a while but for most part it was smooth except for 1 thing:
Permissions to certain old files were denied as I changed the username on my new system.
So in order to access the old files owned by the old user account I had to add my new user to the old group.
The group information is stored in the netinfo database on mac os x unlike traditional unix/linux systems where it is stored in /etc/groups file.
The command I used was:
nicl -raw /var/db/netinfo/local.nidb -append /groups/olduserid users newuserid
I also added myself to the admin group which will give me access to root files.
nicl -raw /var/db/netinfo/local.nidb -append /groups/admin users newuserid