Installing clamav gem on Mac OS X with Homebrew-installed clamav

gistfile1.txt

$ env ARCHFLAGS='-arch x86_64' gem install clamav 
Building native extensions.  This could take a while...
ERROR:  Error installing clamav:
	ERROR: Failed to build gem native extension.

        /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb
checking for clamav.h... yes
checking for cl_engine_compile() in -lclamav... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
	--with-clamav-dir
	--without-clamav-dir
	--with-clamav-include=${clamav-dir}/include
	--with-clamav-lib=${clamav-dir}/lib
	--with-clamavlib
	--without-clamavlib


Gem files will remain installed in /Library/Ruby/Gems/1.8/gems/clamav-0.4.1 for inspection.
Results logged to /Library/Ruby/Gems/1.8/gems/clamav-0.4.1/ext/clamav/gem_make.out

$ env ARCHFLAGS='-arch x86_64' gem install clamav -- --with-clamav-include=/usr/local/Cellar/clamav/0.97.3/include --with-clamav-lib=/usr/local/Cellar/clamav/0.97.3/lib/x86_64/
Building native extensions.  This could take a while...
Successfully installed clamav-0.4.1
1 gem installed
Installing ri documentation for clamav-0.4.1...
Building YARD (yri) index for clamav-0.4.1...
Installing RDoc documentation for clamav-0.4.1...

$ irb
>> require 'clamav'
=> true
>> a = ClamAV.instance
=> #<ClamAV:0x1010e1288>
>> a.loaddb
=> false
>> a.scanfile('/tmp/eicar.com')
=> "Eicar-Test-Signature"
>> a.scanfile('/tmp/l')
=> 0