The Blue & White G3 was one of the first Macs to have a FireWire port, and it does not have the ability to do FireWire Target disk mode FROM the Blue & White TO the iBook. This article also lists supported computers:
58583- How to use FireWire target disk mode
You could reverse the direction of which disk is shared. This would mount the iBook drive on the Blue & White's desktop. You would have to drag and drop your files by hand -- I don't thing Apple's utility program will work automatically in reverse.
The other solution is to set up a small Ethernet network. This is appealing if you already use an Ethernet connection to the Internet -- you have the cables and you have used the Preference panes at least once.
