mac install instructions fail for libusb-devel

What steps will reproduce the problem?

1. Run "sudo port install libusb-devel +universal"

--->  Configuring libusb-devel
Error: Please do not install this port since it has been replaced by 'libusb'.

2. Run "sudo port install libusb +universal"
--->  Fetching archive for libusb
--->  Attempting to fetch libusb-1.0.9_0+universal.darwin_11.i386-x86_64.tbz2 from http://packages.macports.org/libusb
--->  Fetching distfiles for libusb
--->  Attempting to fetch libusb-1.0.9.tar.bz2 from http://distfiles.macports.org/libusb
--->  Verifying checksum(s) for libusb
--->  Extracting libusb
--->  Configuring libusb
--->  Building libusb
--->  Staging libusb into destroot
--->  Installing libusb @1.0.9_0+universal
--->  Activating libusb @1.0.9_0+universal
Error: org.macports.activate for port libusb returned: Image error: /opt/local/lib/libusb-1.0.0.dylib already exists and does not belong to a registered port.  Unable to activate port libusb. Use 'port -f activate libusb' to force the activation.
Please see the log file for port libusb for details:
    /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_devel_libusb/libusb/main.log
To report a bug, follow the instructions in the guide:
    http://guide.macports.org/#project.tickets
Error: Processing of port libusb failed

3. Run "sudo port -f activate libusb"
--->  The following versions of libusb are currently installed:
--->      libusb @1.0.9_0
--->      libusb @1.0.9_0+universal
Error: port activate failed: Registry error: Please specify the full version as recorded in the port registry.

4. Run "sudo port clean libusb" and "sudo port install libusb"
--->  Activating libusb @1.0.9_0
Error: org.macports.activate for port libusb returned: Image error: /opt/local/lib/libusb-1.0.0.dylib already exists and does not belong to a registered port.  Unable to activate port libusb. Use 'port -f activate libusb' to force the activation.
Please see the log file for port libusb for details:
    /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_devel_libusb/libusb/main.log
To report a bug, follow the instructions in the guide:
    http://guide.macports.org/#project.tickets
Error: Processing of port libusb failed



What is the expected output? What do you see instead?
Expect correct installation

What version of the product are you using? On what operating system?
OSX 10.7

Fixed by running

"sudo rm -f /opt/local/lib/libusb-1.0.0.dylib"
"sudo port clean libusb"
"sudo port install libusb +universal"

Basically the Mac install instructions need to be updated and should include a warning that the short install may leave files around that will need to be deleted before installing with port.