l have a G35X 2004, but l got the new keyless remote for the G35 07, So l was wondering if l can do it mayself or l do l need to go to the dealer?

If you can understand the manual that came with the car/unit then you should be able to figure it out. l know most of the time they put instructions in there that not even a person with a PHD in English can understand. If the manual is to complex then take it to the dealer and have them demonstrate it too you so you can see hands on how it is done. That’s often the best way.

l would definitely take it to a dealer.

l doubt the dealer can do it for you. Your 2004 was not equipped/programed for the new keyless remote, let alone push button start. This is most likely aftermarket and will need to go to well known car audio installer to install it for you. l would go to the car dealer first and ask them, but my guess is that they will not install that for you. Anything aftermarket, they will not touch..

Good Luck!