Yeh, Sections 1 to 12 of 'Follow the Dog' would be fine for him,
http://homepage.ntlworld.com/shenton22/chase-trails/map/The boardwalk mentioned in the previous post is the skull & crossbones actually on S7 on the map, but in addition, I would also avoid the stream crossing Btw S2 & 6 which is the rock slabs and woodwork next to the pond, as the drop off the woodwork is a bit severe. Just turn right at the end of S2 and ride past the pond.
Section 13 is more technical, so I would suggest a fire road route back until he gets a bit more confident.
there is also the timber drop at the end of the climb at section 8, but this is possible to dismount and walk down (in fact he may already be walking by then as that switchback climb is a bit of a drag)
Some of S8 can also be a bit lairy if you dont control your speed, the little jumps arnt exactly best placed with some trees in close proximity
It might be best to miss all of S8 and do the signed 'short' route
I think the old sections FtD 3-5 that are no longer in use are still ridable, just not maintained. They may be a good place to learn as there will be no one else around. I'll mark them on a map for you when I can, likewise the old 15-17 (although the start of these have been brashed)