I had 101 ArPen on Olaf...with health quints! Items:
1) Jungle to wriggle's
2) Berserk boots
3) Avarice blade->brutalizer->Youmuu's
4)Warmog's
5) Atma's
6) Sword of Divine(!)
7) Sell wriggle's to get Frozen Mallet
So, in total: 21 ArPen from masteries and runes, 30 from ulti passive, 20 from youmuu's, and 30 from SoD's active, in conjunction with the active from youmuu's and W and any odd buff you may have, that's a 2.1 AS 101 ArPen Olaf for you
Of course this build leaves your HP as your only defence, but Olaf really feels like a lifesteal champ, so I can't think of anything better than this.