What should I spec to prepare for killing ice boars and frostlocs in Northrend?

Shadow with Dispersion
http://www.wowhead.com/?talent=bVcMZZGbfbRrkciqfzVo

Shadow with Meditation
http://www.wowhead.com/?talent=bVcM0hZZGbfbRrkciqfzc

Depends on whether you want full damage and Dispersion immediately, or full Meditation immediately. After picking up the one you didn't have right away, either Mental Agility or odd things left out in Shadow will work.

Non-Shadow with Surge of Light
http://www.wowhead.com/?talent=bVcMkhxtrZrxt0cbqbZh

Non-Shadow with Reflective Shield and Power Infusion
http://www.wowhead.com/?talent=bVcMkhxtr0sZrxt0cbsZh

Holy does not have good solo talents deep in the tree. Discipline has Penance, but you would have to give up Searing Light or Spirit Tap. I don't recommend deep Disc while leveling.

The two hybrid builds above are pure preference; they both focus on increasing Spirit stat and Spell power synergy. For either one, just work towards the other one to fill up on Holy based damage as you level in Northrend. Sprinkle in extra healing (e.g. Spiritual Healing) or extra defenses (e.g. Focused Will) to taste.

EDIT - Fine, Discipline fans, if you want to give up 10% damage for Smite and Holy Fire, I recommend waiting until level 73 then going for something like this:
http://www.wowhead.com/?talent=bVcMuhhtrosVbRt0xxZh