Yeah, that seems to be the sad state of the situation. So since it is hard to get hold of firmware, chances increase that it is old. Did i understand you correctly that you had tried with Postscript some other way, and it didn’t work? Maybe contacting support could be a good idea.
If you have it working with CUPS on a Linux machine already, you could share the printer from it, and use that. But that’s of course no fun with a nice printer like that.
If you have the SDK set up and feel comfortable changing a little code, you could change ippprinter.cpp at roughly line 134, so that it does the following unconditionally:
_additionalDocumentFormats.append("application/pdf"); _additionalDocumentFormats.append("application/postscript"); // and maybe even add this for good measure _additionalDocumentFormats.append("image/urf");
If that works, your printer is the first confirmed case of something that supports reasonable formats but with no way of detecting it.