Always ensure that you have the latest drivers installed on both of your computers.
Now, for this particular issue, first you must know the XP 32 bit computer name and printer name.
When you have the Computer name and printer name on you, you can then switch to your windows 64bit computer and there GOto - controlpanel - printers - addprinter - add a local printer - then click ‘Create a new port’ - ‘Local Port’ - then click ‘Next’.
This is the port name ---- \\Computer name\printer name
So enter the names and click ok, and you're done.