It's pretty much the same as adding a local printer in CUPS, but you just point it to the remote printer instead.
First thing, look at
http://www.linuxprinting.org/show_pr...um=HP-PSC_1210 You're in luck, as it looks like HP provide an open source driver for the printer. Download and install the relevant PPD file from that page (basically, grab the PPD file and put it in the /usr/share/cups/model/ directory)
(I don't know how much experience you have with CUPS, so I'm assuming 'none but learns quickly')
Then, go to
http://localhost:631 in your browser and select 'Manage Printers', then click the 'Add Printer' button - username and password are 'root' and root's password.
Fill in the first boxes, and then click continue. From the drop down box in the next screen, pick the last option, 'Windows Printer via SAMBA'. In the next screen, enter the device location. LinNeighbourhood, I imagine, should give this to you - if not, it will be something like (off the top of my head):
smb://<wife's machine name>/<printer share name>
Then continue as a normal printer - select HP from the next menu, and then the driver you downloaded and installed, and you should be ready to go.