In general, forward secrecy (PFS) should be enabled if you have the Diffie-Hellman (DHE/EDH, ECDHE) ciphers enabled.
Please note that MWG currently does not support EC ciphers. The output states that Forward Secrecy is not supported with SOME browsers... you may want to check the handshake simulation and verify which do not support Forward Secrecy. It seems for some versions of Internet Explorer on < WIndows 8 you need EC ciphers to set up forward secrecy. As MWG does not know them PFS currently fails for those browsers.