altima push button start

It is possible to do - I've done it.

I built a custom circuit to interface with all the LEDs and the start/stop button.

Here is a thread on here about the entire project:   https://www.the12volt.com/installbay/forum_posts.asp?tid=94396

Here is a YouTube video of it installed in an RX-7:

As of right now it still needs a key.  My goal is to develop an RFID interface that will do all the ignition switching by itself.  Then, the last hurdle is getting past the mechanical steering wheel lock.

I don't want to say no, but I wouldn't want to try it.  The pushbutton system is basically wired in to the entire car.  You would need to buy a BCM, an ECU, and all the antennas (I think there are 5 or so) to make the system work.  You would then have to wire them all up and somehow make the canbus work properly so the BCM and ECU would communicate.  The ECU would have to be wired to run the motor, as that is how the pushbutton start system works.  I don't see that being very feasable, but it could be possible.

That might work if you just want "start" and "stop".  You won't be able to cycle through different ignition/acc/start patterns.  You should also incorporate some sort of "engine running" signal in to the mix to insure that the module won't try to crank the starter if the motor is already running (ie get out of sync).

You will also need to bypass the mechanical steering wheel lock to get away from needing a key and you should incorporate some sort of added security to prevent people from driving off with the truck.

Anything is possible if you have the time and knowledge to build it!

By itself, though, the Altima button only has one set of momentary switch contacts and individual (-) inputs for each LED and one for the backlight.  As mentioned above, you'll need to design a control system if you want the Altima button to do anything fancy.