Ignition substitute/replacement

Bought the car for $100.00 it had the ignition ripped out and currently using a screwdriver type key. I think the car is one that it turns to accessory when you turn the key backwards and it keeps getting turned all the way back and draining my battery. I think I would like to put a rocker switch in it instead of replacing the ignition pieces since my crew has a problem with finding the hole and not breaking keys. I know this isn't the standard best solution but it would work best for my drivers in this car? So can I replace the whole thing so that it is start and stoppable with a button or switch instead of a key being needed and how would I do that? It seems like I would just take it off and wire the existing wires to the switch but don't want to mess it up in case.