You could use a localtalk to ethernet bridge. I think 10.5 still supports the appletalk protocol.
look at
http://www.asante.com/products/CardsAdapters/AsanteTalk.aspI have had localtalk 7.x machines talk to ethernet Mac OS 9.2 machines successfully via the asantetalk
I will warn you, localtalk is sssllllllooooowwww, but otherwise works well.