Best I ever did was nullmodem to my PC, run STerm on the PC and telnet thru it. Works pretty well if you don't mind working in all text and no better than 9600 baud. ;-) 19,200 on IIgs.
I'm pretty sure, actually certain that the apple IIe can do 19,200 baud. I used that speed for all my ADT transfers back when I had it up and running last time. Specifically, when the smoke seals were all still intact. [As you know, recently my apple IIe sprung a leak, and lost nearly all of it's smoke]
I was using an Apple Super Serial II card. I'll be scanning up some of the genuine article manuals sometime in the near future. They may be a little fat though, so I'll need somewhere to host them for everyone to get their own copies.
Does anyone here have about 5 - 10 MB of hosting space available for this cause? (I have nearly maxed my own hosting space, which is a pitifully uncharitable 5MB from my tightarse ISP.)