Running 32-bit program accessing USB port on 64-bit Linux

["Martin Payne" <martin@microcosm.co.uk>]

I have installed AMD64 Linux (unofficial Sarge release).
I have also installed libusb-0.1-4 package and ia32-libs package.

However when I run a program I compiled on 32-bit Debian Linux (which works
under this OS) I get the error:

Error while loading shared libraries: libusb-0.1.so.4: cannot open shared
object file: No such file or directory.

It is there, but I guess it is 64-bit and not 32-bit. How do I install the
libusb-0.1-4 package for 32-bit programs running under AMD64?

Thanks!