Stay On Target
This addon will work like a focus target but works only for the misdirect ability for hunters. You can set a hotkey to the spell if you wish, in fact, that probably works best. If you like clicking, the button works too.
No configuration required. Will just exit if the current player does not have the misdirect ability. Set your target with a right click on the misdirect button and select it from the menu. Can only choose party or raid members and pets. If none is the target then the spell casts normally.
Right Click drag to move the frame around to where you want it. Left click the button to cast or set a hotkey using the Blizzard key bind interface.
Will remember your target setting in case you lose connection but will intelligently clear it if you leave a party or the current target leaves the party (or raid).