Tech Support people are the lowest-paid and least-trained in the computer business - don't always count on their answers!
Did he give you any other info? It's true Xante drivers aren't built-in on OS X. Did you tell him you downloaded and installed an OS X driver? Since it's a postscript printer, I'm nearly 100% certain it will work (even I could be mistaken, and I don't have that printer to experiment with). I have downloaded the manual and that tells me it will work.
Did you try setting the manual IP address and setting up in Printer Setup Utility or in Print & Fax prefs?