Rat Yorick is a God
Just played a game on the PBE and this build landed me with 350+ CS in a game that lasted about half an hour.

is a must for Rat Yorick. His ultimate has a big, whopping cool down of 160-140 seconds base, so we gotta be looking to reduce that crap. Also, lowering the cool down of his Q is amazing and lowering the cool down of his W and E also helps him to help smarten up his ghouls and escape from any angry defenders. The Summoner Spell reduction also helps Yorick set up the legendary 3 lane push much quicker.
helps Yorick himself push a tower and 1v1 if needed. He also benefits from every stat it provides, which is rare among it's users usually. The CDR it provides is also much appreciated. He benefits from both passives as well, benefiting from Rage to help him flee a fight and Spellblade to knock down them towers.
is the first pushing item you should get. Get either this or Trinity Force first based on how your lane is shaping up and who is your opponent. I don't really need to explain why this is a must on a build called Rat Yorick. Once you have this, you can begin the legendary 3-lane push consisting of: Yorick Lane, Item Lane, and Maiden Lane.
is the second pushing item to get. You should probably place this in the lane with Zz'Rot since Zz'Rot by itself is good, but not quite equal to you or your Maiden's pushing force. With this, the gap of power is slightly equalized.
is what will then widen the gap a little. Without this, Yorick isn't just incredible by himself (and I mean without ghouls). With this, the lane he is in becomes a serious pushing threat that requires the enemy to draw attention away from your Maiden, your Items, and your team. Once you get this, you will REALLY start to rack up the minion kills. Note that getting this many items in an average game is entirely possible since you are essentially getting gold from 3 different lanes in your prime.
The final item that I can't really nail down, so I just included an item with some nice synergy. I assume Yorick is healed through this item by the damage dealt by his ghouls, so this is a huge sustain engine for Yorick later in the game. I'm not sure if this is worth buying over a Ruby Sightstone simply to lower the cool down of Zz'Rot and Banner of Command, but I have a feeling it is since it's giant attack damage bonus really helps Yorick's ghouls and Maiden with dealing extra damage, which, no offense to items, are a lot better at both PvE and PvP.
Seriously, this is what you guys should be planning on dealing with (at least from me) once Yorick is released. My brother is trying out Yorick jungle, which requires more thought then you think to get those precious ghouls to make his clear speed temporarily god-like by last hitting 3 minions with Q per camp. His W is also a decent ganking tool, but whatever, this is a Rat Yorick post, not Jungle PvP Yorick post. You have 2-3 weeks to prepare for this pushing machine, so prepare your soon to be rotting bodies for the Shepherd.