Yes you can, and it's very easy to do.
Bear in mind you still have the option to do "1-Wire" if you are prepared to forget the standards and drop the speed down. It's only the fact that the official 1-Wire standard specifies how long each pulse must last, and that those timings can't be met on a long cable that are the issue. If you slow it down to give time for the signal to propagate it will still work but of course not be compatible with other 1-Wire products.
Firstly, RS422 and RS485 are not protocols, they are electrical specifications for sending data down wires. The format of the data is still your choice. They are very similar, the primary difference being that RS422 is a one-way system so two links are needed to provide a return data path and RS485 "time-shares" on the same wires. Both are differential systems and can withstand a reasonable (a few volts) difference in ground potential at each end because the polarity and difference in voltage across the wires is used to carry the bits rather than an absolute potential above ground. The other benefit to differential transmissions is that because the bit transistions cross over simultaneously on twisted wires, the net electromagnetic radiation is reduced and similarly, signals picked up on both wires simultaneously are cancelled out. this makes them far less prone to radiating or picking up interference, something you have to consider on long cable runs.
Both systems are driven directly from the EUSART and feed incoming data directly to the EUSART. Many devices are available to convert standard logic levels to the RS422/485 levels. I use ADM488 and ADM489 devices by preference but many manufacturers produce theit own versions. Note that only one transmitter can drive a line at a time so you have to manage the "transmit enable" signals in your software. Usualy this is nothing more than a line of code to enable the transmitter at the start of your data and the same at the end to disable it again. The only other thing you need is a terminating resistor across the wires, preferably at the far end of the lines and a pair of steering resistors to maintain a small voltage across the lines when no transmitter is driving. If you don't fit the steering resistors, when no transmitters are enabled, there is a risk of the voltage across the lines falling in "no mans land" and random noise coming out of the receivers.
Look up the data sheets for those devices and you will see it's easy to do.
Brian.