Runes: All Cooldown Runes. I'll leave it up to you to decide whether or not to go with Level or Static Runes. Just note that level runes won't equal static runes until about Lv13. You should be able to hit around -16-18% Cooldown with a full page.
Boost - Removes snares/stuns + Spell Shield. An excellent escape spell. Main power is the very, very short cooldown (only 2 minutes, compared to 4 min for Speed Up, and 5 minutes for Flash). The real power is that you can use it pre-actively to absorb a spell as well.
Clairvoyance - No explaination necessary
1&2) Astral Blessing/Infuse - Getting Infuse earlier lets you keep up with your lane-mate's spammage, but you run the risk of not having a heal available until Lv2.
3) Astral Blessing
5) Astral Blessing
6) Infuse (Wish does too little at this point in time, and Lv3 Infuse's 150 mana is just too damn good to pass up)
9) Astral Blessing
12) Astral Blessing
14) Star Call
15) Star Call
17) Star Call
18) Star Call
1) Boots of Speed
3) Potion of Sight (if fighting Twitch/Evelynn. You don't want to get ganked, and wards' 30 sec stealth detection is unreliable)
4) Whatever you feel like. I personally usually either go with a Boots of Swiftness (to maximize my escape ability), or Banshee's Veil for more the HP buffer/spell shield so I get a nice dual layered shield with Boost.
Hints & Tips:
-Make no mistake. You're pure support with this build. Partner with the most heavy hitting character on your team (ie: Twisted Fate) with low cooldowns and have him spam those spells. Personally, my fav champion to lane with is Alistar, since Alistar can AoE heal your creeps, while you can restore Alistar's mana. This makes extremely relentless lane pushes and your creeps just won't die until they reach the turret.
-Spam wards whenever the cooldown is ready to prevent ganks, since you're the primary target.
-Use Boost pre-actively to absorb a spell.
-Remember to cast Infuse whenever its ready, and Astral Blessing your melee before they charge in, not after, since you want to make use of the +armor buff as well.
-Remember, Wish will heal every single teammate regardless of range. If you have voice communication avaliable, let your temmates know to call out Wish if they badly need a heal and you're not in range.
-In terms of positioning, do not, I repeat, do not remain in the rear of your group unless the entire enemy team is accounted for. You run the risk of being ganked otherwise (especially if there is a Evelynn and/or Twitch on the other team). Try to stay in the middle until you're absolutely certain you know where everyone is.
-You won't make a lot of money with this build, unless you're damn good at constantly last hitting Creeps. The reason why you'd stop at Lv1 Boots is because you want that Locket ASAP as it boosts your HP/Mana regen skill by so much yet is so costly. To be honest, most games I've been in using this build ends around Lv13, with me only making enough money to get the boots of speed and locket.