Additional arguments to configure

[Patrik Johansson]

Hi guys!
I'm trying to install Irssi with proxy support.

On of the arguments to configure in the portfile is --without-proxy

==Snippet from the portfile ==
configure.args  \
         --without-socks --without-bot --without-proxy \
         --with-modules --enable-ipv6 --enable-ssl \
         --with-perl=no --with-glib-prefix=${prefix} \
         --mandir=${prefix}/share/man
== End of snippet ==

Is there any easy way to change that argument to --with-proxy so I can 
build Irssi with proxy-support?

//Patrik J