There are a few videos floating around YouTube of Gadd talking about his approach to this tune and breaking down some of the licks. Not that there's a whole lot to break down. He isn't really re-inventing the wheel here (a lot of hand-hand-foot in varying rhythms) but the orchestration is absolutely beautiful and it's executed with a pocket like only Gadd can. And it's said that he sight read the chart, and nailed it by the second take.
At the end we even get to hear the classic "Gadd samba", which I personally never really consider a "samba", but that doesn't mean it's any less killing.
Also, be sure to check out "The Making of Aja", which can be found on YouTube. It's a wicked documentary with Donald and Walter talking about the making of the album and interviewing some of the musicians. They even break out the masters and play some scrapped parts in context, and mute/solo certain tracks. Very cool stuff.