At level 63 I am able to make a simple macro, "/cast snake trap" and put it onto a bar. This spell doesn't work on its own until you cast [Trap Launcher].
[Trap Launcher] is trained at level 48.
[Snake Trap] is trained at level 66.
I add a [Snake Trap] macro onto my action bars. (Typing /cast snake trap in chat also works, but who wants to do that every time?)
[Trap Launcher] is activated. Notice how the macro is no longer grayed out.
[Snake Trap] reticle.
And there it is.
A friend helped me confirm it on his 60 Hunter.
Any 48 - 65 Hunters looking for some extra fun in BGs? Try it out.
Edit: The title is misleading. It took some research on the level [Trap Launcher] is trained to realize that [Snake Trap] is probably the only thing that you will get earlier than its required level.