Just to be precise, is the question "I have a team of developers, and I want to make those specific developers enthusiastic about software development", or simply "I want a team of enthusiastic software developers"? In the latter case, simply don't hire people who aren't enthusiastic.
In the former case, you're pretty much screwed. It's hard to change someone's personality so much that they start to care about something they didn't really take an interest in before. Of course it can be done, but let's face it. How many here have been unable to convince their better half that programming is interesting? For that matter, how many people have failed to adopt their girlfriend's enthusiasm for shopping, or shoes? ;)
Convincing people to share your interest and enthusiasm for something is hard work.
Unless you're willing to set aside a few years of your life for getting into the head of each individual developer, getting to know them and what makes them tick, and gradually push and prod them towards taking an interest in something that they previously simply considered a job, you're probably better off letting them go and hiring people who are motivated to begin with.