I agree with Buttercup, and I'll add Spot, Listen, Sense Motive and Search to the skills. All maxed out of course. He's going to need to have most of his levels in Rogue, for the skill points. Aristocrat or expert would be just a flavor thing; IMO they're not really needed, rogue being generic enough. The 18 INT will help, giving him a total of 13 skill points per rogue level, 52 at first.
His skills should be Spot, Listen, Search, Gather Information, Sense Motive maxed out (using up 5 of his 13 points/level). He still has 8 points/level, which he should divide between Appraise, Disguise, Bluff, Diplomacy, Forgery, Hide, Move Silently and a good number of Knowledge skills.
As feats, he should take a few Skill Focuses, Iron Will, and... well, I dunno, I'm not an expert on the topic and feats are fairly specific things.
As his Rogue special skills, he should choose Skill Mastery once or twice, and maybe Slippery Mind.