I'm having trouble finding a decent F23A5, but there are endless numbers of F23A1/A4 engines available for good prices. Htmotorsonline has plenty in fact. What do I need to make the A1 motor work on the Accord DX which originally came non-vtec?

I know there are other swaps I could do that would be more exciting, but my main focus is reliability and smog legal.

Is there a guide or does someone have some good instructions on how to add Vtec to the a non-vtec car? Is it possible? Do I need a different ECM/ECU?

Thanks