I am not sure if this will work for everyone but I figured it might help someone since there is limited info for this issue, so here is how I got it working.
Install your drivers to your XP machine fropm whatever source your have - I had to get mine at HP.com and installed from an .exe file.
The go use Add Printer : "Add Printer Wizard" > "A Network printer or one attached to another computer" > "Connect to this printer".
When I got to this stage I typed in \\ and then the workgroup for the buffalo, which for me was "BUFFALO". It will actually show up in the dropdown if your computer can "see" the printer server on the network.
(TIP: if needed, check under My Network Places > Entire Network > MS Windows Network > Workgroup to see what yours is called.)
Once you had added the path, it will likely error and allow you to select the Hardware Manufacture and driver, or give you the option to use the "Have Disk..." feature. I could not find the correct printer in the list given, and the have disk was not working when I browsed to the extracted drivers I downloaded. So I picked anything just to get in to add any printer from HP.
After it added the printer, and even tho it gave me an error, I was then able to go to the properties of the printer and go to the Advanced tab to select the driver I installed beforehand.
Of note: I am not sure if this Advanced tab was only available because of the random driver I did select or not, so good luck! If I learn any more on this topis I will update this post.
SR
