You could fake that, to some extent, with WRCBE and a command block: The "wand" is a wireless remote tuned to a frequency on which there is a wireless receiver attached to a command block with the given command. However, you wouldn't be able to reliably have it do something on or relative to the player with the remote- since @p targets the nearest player to the command block, if there's someone closer to it than the remote-holder, they'll get the effect.
As for the concern about players hacking this system by using another remote tuned to the same frequency, WRCBE provides a solution as well. One of the items (Personal Sniffer or something) allows a player to lock down channels, so only they or a server op can set transmitters (or remotes) to them.
Hmm... I know the latest versions of ComputerCraft feature creative-only Command Computers that can execute commands like a command block. Do they come in a tablet form, does anyone know? And more importantly, can a non-OP, non-Creative player do anything at all with a pre-programmed Command Pocket Computer?