Honestly, I wish I was even a little good at modding that I could do this myself, it's such a small thing to request. Anyway, I'm sorta new to these forums and I was wondering if any modders with spare time could create a small file (probably only 1 class or whatever would need to be changed) that simply changes the damage that snowballs do to half a heart to all mobs. I'm hoping to have this work for both players and snowmen. If you do make this, I'll mention you in the youtube series I'll be doing that will be possible thanks to this. Other than that, there's not much I can offer you, sorry. But, if you do even attempt to help me out this way, then you are a saint and a beautiful man/woman who will forever go down in my heart as the most awesome individual to grace the galaxy. I feel like I should sign this off so...
(PS: If you make it, you should message me and post the public link (dropbox, google drive, mediafire, it doesn't matter) in the comments so that anyone can download it if they want a similar mod)
(PSCEPTION: If the easiest way to do this would be without a mod, please explain it to me very explicitly because I'm really stupid. I'm not doing this for a server or anything so don't recommend me Bukkit please)
I know you said not to recommend bukkit, but if you're just doing this on single player, it would still be very easy to set up a bukkit/spigot server and install a snowball damage plugin and you be the only person on the server. I also believe there is a mod called bukkitforge that allows you to install bukkit plugins using forge.
THANK YOU MY BROTHA YOU ARE A SAINT! Seriously though, thanks a lot, the mod works perfectly fine. I don't need a custom death message because I intend to use it only for singleplayer, but thanks for offering.