Hi,
The secret is in the making of the Postcript file.
In the print setup box choose Acrobat Distiller as your printer driver. Then in the paper choose custom as the paper size, add the bleed you need for your original document. click the option " add printer marks" and also "center page in print area".
It is possible that you get the message 'that not all of the information will fit ob the page" and the question if you want to print anyway, click on print anyway
Afterwards you distill it and voilà the bleed is now in your PDF
Hope this helps
grillhouse