Can a person prove that Jesus Christ is in the Old Testament without going to the New Testament? Sometimes as christians when we are talking to the Jews, we tell them the Old Testament refers to the coming of Jesus Christ. It's like we are forcing our beliefs unto them by using references from the Old Testament and adding Jesus Christ there.

How can you prove or is it possible to prove to a Jew from a book (New Testament) that they already reject that indeed Jesus is the awaited Messiah?

Without the New Testament, I think it's impossible to prove that Jesus is the long awaited Messiah. It's like a Muslim telling us that Mohammad is the comforter by using the Qur'an. While we already know that it's the Holy Spirit.
In Luke 24, Jesus says this to the two men walking to Emmaus:


  25 He said to them, “How foolish you are, and how slow to believe all
  that the prophets have spoken! 26 Did not the Messiah have to suffer
  these things and then enter his glory?” 27 And beginning with Moses
  and all the Prophets, he explained to them what was said in all the
  Scriptures concerning himself.


It appears that Jesus was capable of proving the point. That does not mean that we possess sufficient clarity concerning the meaning of the scriptures to do what he did, but we can through prayer, careful study, and experience approach that goal.