ok, three things here....
One, I have a friend that is absolutely smarter then anyone here ( not to be an ass... but he is a mathamitition ) when it comes to math. Altho he does not believe in time travel he does see the logic in this and says this is this possible.
Second, it wouldn't happen now anyways. My other dimensional will not just appear beside me. The reason is that I'm still new in thinking. Tommorow, I might change my mind about something. The trick here is to have a realistic plan. A path that only ends with one result ( in this case, a future time traveler gets my message and complies ). Also, aside from thinking about it... taking actual actions plays a huge part has well. Its not going to be just enough to think it up. The work is minor tho.
Last, messages can ( and are carried out in many ways ). It is a fact... that NASA has sent messages out into space via laser beam ( and possibly received a response ). Books written in stone! Really, there are a million ways to send a message.