It's easy to get it working if you have Miami(DX) and a linux box.
use the built in serial (PPP/CSLIP) driver in miami (or some other faster alternative like 8n1.device ) and in the modem tab choose "null modem" . The rest of the options can work with the defaults? i have no amiga here atm.
enable ip forwarding & masquerade on the linux side and issue the command:
"/usr/sbin/pppd /dev/ttyS1 38400 noauth local passive proxyarp asyncmap 0 silent persist 192.168.100.1:192.168.100.2 " remember to have the same serial speed on both the amiga and pc, 38400 works on my A2000 with A2630 @ 25Mhz