In case u still wanna do this there are 2 way to do it, the easy way and the not so easy way.

Easy way is that u replace the exact same file with ur own, in your case it's "AttackKamikaze.wav" located in SS3 game directory:

Serious Sam 3\Content\SeriousSam3\Sounds\Enemies\Beheaded_Kamikaze

If the folders don't exist u must create them.

The not so easy way is that u open the Kamikaze model in the Serious Editor and edit the Sound parameter. To do so open the Editor then go to open File>Open>Document.Model and navigate to Content\SeriousSam3\Models\Enemies\Beheaded and open Kamikaze_SS3.

Once opened select the config tab at the bottom left and expand the CModelConfiguration>Schemes>Sound scheme>Terms [3]>[0]>Variations [1]>[0]. There under Sound you'll see "AttackKamikaze.wav". When u hover over the name it will give u a preview of the sound. Simply click on it and navigate to the new sound u want.

This way u can edit some parameters which are not possible in the easy way.