Wrote a little macro addon to track your killcount and experience over time. Spams experience gains and average time to kill each mob every 6 minutes.
Only briefly tested but should work with any macro.
Works best for actual melee toons, casters may or may not see the slain message that triggers kill event.
Updated to correct minor XP tracking error and division by zero error.
Update 8/18/16: simplified the call routine, makes it easier to add to macro.