An external option is pretty much the only thing you can do.
With IS Boxer, you can send the command (hotkey) to disable Jamba Strobe.
And also send a directional movement key (like down arrow).
On the same mapped key.
You are technically pushing one key, but wow receives two keys.

Similarly, a one-boxer could have two keys next to each other hotkeyed.
One to move backwards and one to disable strobe.
And press the edge of both keys, which is one finger motion and two keys pushed.
Or go with the penny glued across two keys method.