Can you train yourself to like certain foods?

It's certainly possible.

I grew up hating squash, zucchini, cucumbers (and by definition, pickles), but now I love them. Steamed, boiled, roasted etc, they taste delicious to me now.

I found that it was much easier by starting to eat them with things that you normally like eating. If you like soups, cut them up and put them in your soups. For example, squash in shrimp bisque alkjdnslakjngaskjgnanl nom nom.
The good thing about many vegetables is that they're really a subtle flavor that you can mix with just about anything and it'll make itself, and whatever it's going to swim in, taste better.