usb printer assignement

[sandy basickes]

  Our last system was a 3 year old linux software system
that used lprng and had 5 printers:
       3 serial
       1 usb
       1 parellel.
    We now have a new system
 linix 2.6.33.3 #2 SMP Mon Jun 21 14:47:31 EDT 2010 x86_64 GNU/Linux
 and have moved from using lprng to cups(debian package).  We
   now have 6 printers:
       3 serial
       3 usb
   We were able to add and print to the serial printers through cups.
   These came up as they should and could be addressed with their cups name.
   We then added the 3 usb printers:
        ML421 Oki Data (fed with double sheet paper) ( default)
        ML421 Oki Data (fed with single sheet paper)
        Toshiba B-SA4T
   In cups, these were named lp, p1 and tecb respectively.
   The first two Oki printers are the same make and model.

   When the system is booted with all printers powered, the
   printers are assigned randomly to /dev/usb/lp0,
   /dev/usb/lp1 and /dev/usb/lp2.  When we print
   to lp, cups sends the data to whichever printer was randomly
   assigned to /dev/usb/lp0 at startup.

   If we boot up with only one printer powered, then the
   powered printer is assigned to /dev/usb/lp0 with cups name lp.
   If the second printer is powered it comes up as /dev/usb/lp1 with
   cups name p1. Likewise, when the third printer is powered it comes up
   as /dev/usb/lp2 with cups name tecb.

   When powered simultaniously, how can we have the printers consistently
   assigned to the same port and cups name ?
   Is there another way to define the usb printers so that the same cups name
   is always assigned to the same printer?