Scooby, the question is not how to get to it over the wireless, it's how to get to it over the network. There's no difference, as the new computer could be connected by cable or by 802.11, it's the same thing, just a different media. The wireless IS the network. (Think of it as 802.11 being an invisible cable.)
It looks like you're assuming the new computer must have its own connection to the printer, which is not necessarily the case. The printer on the other computer must be shared by that computer. On that computer, open Printers in the Control Panel, right-click the printer and go to the sharing tab and set it up. On the new computer with wireless, go to "add a printer" in the Printers screen of the Control Panel, choose network printer, and you can then browse to find the shared printer.
Now: the fax driver might not come through the network; not all of the all-in-one printers can share all their functions. You might have to download the driver package and install it on the new PC to get the fax to work (as opposed to just connecting to the share.) You might also have to share the fax driver separately on the other PC, as well as the print driver. (2 shares, 2 connections, one to print, one to fax.) Then again, you might try that and find it's not possible.