OK, don't laugh. At least not out loud.

I am trying to connect a usb only HP all-in-one to an OLD Powermac (it's my mom's, 'nuf said) Performa 6320cd with an scsi port and the then typical round din serial printer/modem port. I saw an adaptor from Xircom (now discontinued) on eBay that may have worked, but it was snapped up on a buy-it-now deal before I could return to the site. Now I cannot find anything, anywhere. Does anyone have a clue as to what might work, or where else I could check?? Help!!! my mom bought this damn thing on a whim, and now I'm trying to get it to work for her.

Any ideas would be greatly appreciated.