Doesn't the newer Creo rips have the Adobe Print Engine anyway-so using a pdf is flattening the file. It's the 21st century-postscript is dead.
PDF's and hotfolders are the way to go.
As someone who knows what the man behind the curtain looks like...
PDFs are not God's gift.
Flattening happens.
It's just a matter of when.
...but we're off topic.
To add a (PostScript) printer on OS X with just a PPD:
NOTE: The following is from the Mac OS X "Lion" user experience (perspective). Older OS X variants may vary.
0) Go get the PPD that best describes the desired PostScript device;
1) In the Finder...
2) Select System Preferences (menu item) from the Apple menu;
3) Click Print & Scan (icon) to open Print & Scan (preference panel);
4) Click the Lock (icon) if necessary to make changes;
5) When prompted to authenticate with Administrative credentials, do so;
6) Click Unlock (button) to supply the entered credentials;
7) At the bottom/left corner of Printers (listbox) there are a pair of buttons marked with + and - (icons);
8) Click + (icon);
NOTE: The Add Printer (window) should open.
9) There are four icons labeled "Default", "Fax", "IP" and "Windows". Select (click) the IP button;
10) From the Protocol (menu), select HP Jetdirect - Socket (menu item);
INFO: The trade name for this protocol is AppSocket. You can think of AppSocket as HP's "completely insecure but nevertheless useful printing protocol". It opens a RAW socket on port 9100 and let's you do whatever you <censored/> well please. Sensitive environments should NOT use AppSocket (I think IPP is the best option but that's just one geeks opinion).
11) Enter the IP address of the Creo in the Address field;
12) Enter a name (e.g., My Awesome Creo RIP) in the Name field (this is for your own use ... anything reasonable should do);
13) Enter a location in the Location field (or don't ... again, this is for your own human consumption so we won't tell if you leave it blank);
14) Select Other... from Print Using (menu), then use the Finder Selection drawer that appears to locate and select the PPD from Step 0;
15) Click Open (button);
16) Click Add (button);
17) If prompted for Configuration details supply them (otherwise, you should do so later in Options & Supplies ... not covered here);
18) Go print something!
