Page 82 talks about split profiles, and which parts you combine and whatnot. It specifies that the rider and mount use their own profiles for WS, Str, I, and attacks but for movement purposes you use the mount's move and you can never have the rider dismount. This appears in the cavalry section, but under the subheading "split profile", so I would think it applies to split profiles in general (which is admittedly an assumption). Page 105 under "ridden monsters and special rules", references page 82. It basically says that characters riding monsters are similar to characters riding cavalry mounts, with the same exceptions applying in the case of special rules transferring.
One question (I'll have a read when I get home). Does Charm of the Jaguar Warrior have a "Models on foot only" requirement on the item? If not it might be nice to put it on a Carnosaur Lord...