Ghostscript doesn't have a 'jobtype' switch, nor a suserid switch, so its not surprising that they have no effect. Possibly the post you reference has some more information, but I can't find any such post, maybe you can point to it (URL)
[later]
Setup.ps needs to be a PostScript file (because that's what Ghostscript understands, its a PostScript interpreter). From the documentation you want to set DocumentName, which is a member of the User Settings dictionary, so:
mark
/UserSettings <<
/DocumentName (My name goes in here)
>>
(mswinpr2) finddevice
putdeviceprops
setdevice
The white space is just for clarity. This is lifted pretty much verbatim from the example.
So, you need to modify the 'setup.ps' you send for each job. You can either write a custom setup.ps for each one, or use the 'PostScript input' capability of GS and supply the whole content of setup.ps on the command line using the -c and -f switches. All setup.ps does is run the PostScript in there before you run your own PostScript program (assuming you put setup.ps before your PostScript program on the command line).
This is pretty nasty actually, its not the way devices are normally configured, but the mswinpr2 device was originally written by someone outside the Ghostscript team, and presumably adopted wholesale.