I use an Asante EN/SC adaptor myself but I'm sure this advice will work for the EtherWave

You first want to get a netgear 10mbps switch. This will take the information from your modern 100 mbps router and make it more compatible with the classic mac. So you would run ethernet cable from your modern router, to the netgear switch and then to the EtherWave.

After installing the drivers, you'll want to use MacTCP which you should have installed on the mac to then select Ethernet Built in, then manually set up the gateway settings for dhcp.

I've had good luck with MacTCP but you can also use Open Transport to just set TCP/IP settings to automatic.