plugin or setting that will block snowball PVP

hello Bukkit community,

I'm looking for a plugin or a setting that will disable the knock back from players throwing snowballs at each other, but NOT when they throw snowball at a mob.

I've looked in to some of the plugins that are currently installed in my server:

• Zmod (iZone)
• worldguard
• creativecontrol
• Essentials
• Multiverse

And currently, none of them do the job. The closest one yet is Creative Control which successfully prevents creative mode players from snowballing other players, but then i want that to apply for Survival players too.

Can someone help me out? It would be ideal if i did not have to install a plugin just for this sake, but I am willing to do so if there is no other way to prevent snowball attacks.

I will provide a list of currently installed plugins if necessary.

Thank you all in advance.
--Deathgleaner