this could work:
Side Chain Compressor
http://www.ismusic.ne.jp/slim_slow_s.../index.html#c3
http://www.ismusic.ne.jp/slim_slow_s...SideChComp.zip
for stereo
input ch1: signal input L
input ch2: signal input R
input ch3: key input L
input ch4: key input R
for mono
input ch1: signal input
input ch2: key input
i've been told this one works+it's free...
ps: you could use rewire and hook up fruity or load fruity as a vsti itself!