Printing From Different Network

I am trying to access a shared printer that is on a different network. There are two different networks in a home: Comcast and Verizon FIOS. The printer (HP Officejet 4500 G510g-m) is directly attached to a PC (W7) that is on the Verizon network. I am trying to use the printer from a PC (XP) attached to the Comcast network. Both networks have WLRs installed but they are not turned on. The WLR on the Verizon network is the stock Actiontec modem/router; the WLR on the Comcast network is a low-end TP-Link. This printer doesn't have wireless or network capability. Maybe buying a second printer is the easiest answer, but I would appreciate any ideas. Thanks.