[root@localhost ~]# pkg-config --libs libusb
Package libusb was not found in the pkg-config search path.
Perhaps you should add the directory containing `libusb.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libusb' found
Most likely even hplip uses the same method to retrieve informations about the installed libraries and headers, so that it fails for some reason. What is the output of the following? Here's mine:
$ rpm -ql libusb-devel
the presence of the file in bold should bring to the correct result of the pkg-config command. In any case, whatever be the reason, you're stuck at point 9 now, since this is still a problem of missing dependencies.