Makefile.usbdevs missing from /usr/src/sys/dev/usb

[tcrnmar at ucl.ac.uk]

I've just installed 5.3 for i386 from CDROM and am now trying to get an Epson
Perfection 4870 usb scanner recognised.  I've read many recommendations to edit
/usr/src/sys/dev/usb/usbdevs and /usr/src/sys/dev/usb/uscanner.c, then run make
-f Makefile.usbdevs.

The problem I have is that Makefile.usbdevs and devlist2h.awk are missing from 
/usr/src/sys/dev/usb.  Is there a good reason for that?  If not, how do I get
them in a minimal size download?

I have successfully compiled and run a custom kernel, so I assume there's
nothing much wrong with my kernel sources.

Thanks,

Mark