I think the same way as the poster above me, in a less agressive way though.
Odd, sounds a bit like an owl ,probably due to some of the reverb as well to space it out a little bit.
Any one know what wah alexi uses? its quite a soft sounding one (compared to zakk wylde anyway) and its in the ETID solo as well i think (and other as well , cant think ATM)
He uses wah in RKM