Okay, if I had to do this without AsantePrint and only with 68k Macs I would
(a) use an Mac with localtalk and ethernet to run the LocalTalk bridge (68020 upwards).
( B) use 68030 class machine (eg IIx) running NetBSD m68k to run my macipd/slippery/pppd.
Now you could make the "Mac with localtalk ethernet" run a gateway which does it all, but somebody would have to write it.
Unfortunately NetBSD macs can't use LocalTalk as the drivers don't exist (too software intensive), and A/UX can't have a user level application inject IP packets directly onto the network (slattach does not work with pseudo-terminals), but you *could* hang a serial cable to loopback the modem port onto the printer port to handle SLIP to solve that, but then lose the printer port to do localtalk.