When editing a postscript file, how can I add Document Properties "Subject" and "Keywords"?

Hi:

I am editing a postscript file.  I add some data to the .ps file so when the file is converted to a PDF file, some of the PDF's Document Properties are entered, and other variables are set. 

I can get the PDF Document Property "Author" in my resulting PDF file by adding this line to the .ps file - 

%%For: JohnB

When this line is added, and I convert the .ps file, the resulting PDF file has "JohnB" in its "Author" field. 

Now, I would like to edit my .ps file to have the PDF Document Properties "Subject" and "Keywords" added into the PDF file. 

I tried simply adding to the .ps file -

%%Subject: Birds

But this does not work. 

So what do I need to enter into the .ps file to give me the Document Properties "Subject" and "Keywords" in my PDF file? 

Thanks,

Kevin