Ok, it's not elegant, but you CAN.If you have the Newton Connection Utilities or Newton Backup Utility or Newton Connection Kit (I'm not sure which ones work with the 120) you need to set it up to connect via AppleTalk.
you will have to be running the Classic environment.
Connect a LocalTalk <-> Ethernet bridge to your network, either via a Crossover Ethernet Cable directly to your G4, or thru a hub/Switch/however your Ethernet Network works.
Now, start your connection software, and try to connect via the Connect panel on the newton. It should work. If not, or you have more questions, post back here.
~Marchie
~Chaplain Marchie
68k Macintosh Liberation Army
Holder of the Compact Mac Stick of Justice, with Explodeing CRT head
~~"We are all Mad here."~~