Yes. Others have done it.

It's got a standard ethernet port, so simply plugging it into a wireless ethernet bridge will work. For example, one of the empeg demonstrator vehicles had an Apple Airport base station running off of the car's 12v power supply.

The tricky part is getting the ethernet bridge to talk to the rest of your network. In the example above, you could talk to the Airport base station with an 802.11 card, but not with another base station. This is a limitation of the base station, not of the Rio Car player. Some base stations can be easily configured to talk to each other, some can't. It depends on the base station.

There are other solutions which have been discussed on the Unofficial Empeg BBS, search there using the keyword "wireless" for more details. All of these options involve plugging something into the ethernet port on the Rio Car player, because remember, there's no PCMCIA card slots on the player, and you can't use a usb adapter for that purpose.

Also note that the sleep timeout of the player is an important issue. If you leave the player in your car, assuming it's wired correctly, it will shut itself off after a few minutes and it won't respond to ethernet. So if you're set on synching from your office without removing the player from the dash, make sure to increase the player's sleep timeout in the Emplode software.