Riva:
You will need to determine the format of the Keeloq payload (probably documented nicely somewhere).Determine the key/serial number and discrimination value used to encrypt the Keeloq part of the payload (having the remote in your hand you might be able to brute force it with enough samples or try the side channel method)
Write Arduino code to generate/emulate the Keeloq encryption so you can transmit it.
All in all a very steep hill to climb.
What do you mean format of the Keeloq payload?
I think I should read on how to decrypt keeloq yes? Hmm Will get back to you once I find out something, think it will require a lot of thinking and calculating 
P.S. I saw Nohawk's methods on attacking rolling code, but that is only one time thing right? just to block code from being accepted to use it a later time, but only once?