This tutorial contains three screencasts showing you how to set up sidechain routing in Logic 9, Cubase 5 and Reason 4.

In these tutorials I use a kick drum to trigger the sidechain and use a piano loop for the processed sound but obviously you can apply this technique to any two sounds you wish. I have also included the project files from each DAW so you can load them up yourselves.

Setting Up Sidechain Routing in Logic Pro 9

Setting Up Sidechain Routing in Cubase 5

Setting Up Sidechain Routing in Reason 4