Had the same problem when porting to CS5.
Changing the prefix from Adobe is not really an option... at least not a very good one.
I solved this problem by not using the number from Adobe but the internal kSDKDefDialogResourceID
// Dialog resourceID:
#define kSomeDialogResourceID kSDKDefDialogResourceID + 1
#define kSomeOtherDialogResourceID kSDKDefDialogResourceID + 2
#define kYetAnotherDialogResourceID kSDKDefDialogResourceID + 3