I'm driving a 2001 honnda accord coupe 2.4 (4 cylinders). My question is can I replace the 2.4 to a 3.0 v6. If yes along with the engine what other changes should be made.

Are you looking for more power ?

As long as that car could have come with the 3.0 it is doable but the amount of money it will take is NOT worth it. Spend some money improving the performance of the 2.4 engine.

I can see you needing a new wiring harness , some of the periphal items like A/C etc may not fit where they are now , trans connections may not match , computer will need to be replaced, motor mounts , exhaust... This is not like days of old when you could take a 6 cylinder out if an old Chevy Nova and put a 350 V8 in without a huge investment.