To make the FX work in L4D2, you have to download the .sp file in the original posting then make a couple of very simple changes.
Open the "adminsmite.sp" file with an editor like notepad or better:
1. Change this line:
#define SOUND_THUNDER "ambient/explosions/explode_9.wav"
To read this instead:
#define SOUND_THUNDER "ambient/explosions/explode_2.wav"
2. Change this line:
g_LightningSprite = PrecacheModel("sprites/lgtning.vmt");
To this instead:
g_LightningSprite = PrecacheModel("sprites/glow.vmt");
3. Find these two lines which are right next to each other and comment them out:
TE_SetupSmoke(clientpos, g_SmokeSprite, 5.0, 10);
To comment them out, they will now look like this (with the two forward slashes):
//TE_SetupSmoke(clientpos, g_SmokeSprite, 5.0, 10);
Thats all the changes you need. Now you have to compile it here: http://www.sourcemod.net/compiler.php
Just choose "Browse", then "Compile". Now download the file it gave you and install it. Good luck.