You could, as suggested use the WPSA-100, be forewarned though, it replaces the LAN drop to the device with itself, so it could get in the way of the current setup.
You can also buy Mobile Print from Xerox for a fee, it works with the printer.
There are a huge list of third party apps and setups.
You can try something like the Xerox Wireless Print Solutions Adapter http://www.office.xerox.com/latest/XWPBR-01U . They don't list the WC75xx as supported though there are some similar devices listed so maybe it'll work. If $200 isn't too muchyou could buy one and test it out. There's some other companies that sell a similar product as well that might be compatibile with the WC75xx