Marks macro's should be fairly simple now.

Hunters Mark, Serpent Sting at the beginning.

Then for macro reasons you could most likely do a SS x 2, AiS, SS x 2, and finally CS again. You might have to add in another SS or two, depending on how much haste you have.

I believe you should be able to make a proc macro with /cast Aimed Shot! that will fire the instant version when MMM procs.

tbh though, SV is much easier to macro, and is the preferred PVP spec... so you might want to consider sticking with that.