Training Older Indian Ringnecks

Is it possible to train a 3 yr old female and a 4 yr old male who have been left alone in a cage together with little human contact? They also aren't particularly fond of one another.

Yes, it is possible but you will need to put a lot of time and effort into it. And then you will need to keep on doing it everyday because they do revert very easily when not handled regularly. And you need to put them in separate cages because sharing a cage when they dislike each other is very, very stressful for them.