There were a few BF42 mods that, on certain maps with certain vehicles, allowed you to spawn in vehicles.
IIRC, Forgotten Hope had a number of para-assault maps that allowed players to spawn inside of the aircraft they would parachute out of.
I believe you could also do this in... I can't remember the name of it, but the Star Wars themed 42 mod (which the BattleFront series either largely copied or was directly inspired by), I think it had some spawn-in-able vehicles as well.
Also BF Vietnam, the official game, used a similar concept of having 'tunnel exits' that could be built/placed by Viet Cong engineers, which were placeable spawn points, and the US had the 'Tango' ... mobile river boat with a helipad thing... which was a mobile spawn point.
I am 99% sure it was BF2 that first introduced being able to spawn on a player, I don't think any of the mods for the earlier games pulled that off always had to be a vehicle or placeable static object.