As a big fan of Slash (Ex-Lead guitarist of Guns 'N Roses) I did some research about his solo style: He uses 2 Somptboxes, a Sunstain Squash Compressor and a Talking Filter... And of course he adds the Crunch/Metal effect!
I figure it out when I was playing on my guitar with Garageband (Mac OSX), I added these 2 Somptboxes and the result was the Solo style of Slash!! :D
George 2Ned