I use the settragetname=x and the activatetarget=x to do this type of thing.
Then have the entity taking whatever action if activated.
Here is how I activate them...
:state=1:settargetname=nameofentityone,state=2
:state=2:activatetarget=1,state=3
:state=3:settargetname=nameofentitytwo,state=4
:state=4:activatetarget=1,state=5
:state=5:settargetname=nameofentitythree,state=5
:state=6:activatetarget=1,state=7
...and so on.
That is how I do it, and then I use something like below for the entity's script...
:activated=1:activate=0,state=1
...then I have state=1 do whatever.
As you can see I set the activated state for the enity back to zero to avoid getting stuck in an endless loop.
Edit
As a side note for new users...the activate=x is not a toggle, so you are not limited to values of only 1 and 0.
You can make it whatever number you want within range, and I am not sure what the range is, but I have had no trouble with activated states up to 99.
So, you can have it doing all kinds of different things and being activated to any of those activated states by any other dynamic entity.
