locking down a scsi device

[Dave]

Hello,
    I've got a 6.0 box that has two burners, one cdr and one dvdr. On boot 
and until the event i'm about to describe when i issue a:
camcontrol devlist
or a cdrecord or the like command the burners are dev 0,0,0 and dev 0,1,0 
respectively. Now whenever i insert either my external usb2 hard disk or my 
256mb memory stick the devices change buses and id's, maybe going to 3 maybe 
to 7 or whatever, they change. Through reading and google i believe the fix 
is to lock the burners to specific device id's in device.hints. I'm not sure 
how to do this as the examples i've seen reference a scsi controller, the 
burners use the atapicam driver not a scsi card. In the same context i'd 
also like to lock down the external devices, so that when they're inserted 
they'll always have known values. Does anyone have a configuration like 
this?
Thanks.
Dave.