Welcome to the dark side.
How can I go about getting my first position as a programmer?
Same as everyone else. You may want to consider a Jr. level developer position since you're starting over in a new field. You're previous experience with Engineering support will give you an edge over college graduates just entering the workforce. You may also want to consider looking for a company with an emphasis on mentoring.
What should I study to regain knowledge of topics from school and to prepare myself for interviews?
The most obvious choice is the language you want to work with on the job and its a good start but you'll also want to read up on more general programming topics as well. A good book on professional software development would be useful. A few suggestions:
- Clean Code - A Handbook of Agile Software Craftsmanship, Robert C. Martin
- The Pragmatic Programmer, Andrew Hunt, Dave Thomas
- Design Patterns: Elements of Reusable Object Oriented Software, Gamma et al.
- Refactoring: Improving the Design of Existing Code, Martin Fowler et al.
- Implementation Patterns, Kent Beck
This is just a short list. See here for a list of the most influential books.
How can I distinguish myself from recent graduates and dissociate myself from engineering support field?
I would use your experience to your advantage. The skills you've learned will give you a different perspective than your fellow developers that came down a different road.
One other suggestion is look to the company you are already working at. Many companies will look internally before advertising an open position. You may be able to make the transition where you already work. That's how I got started. I was a field engineer dealing mostly with hardware troubleshooting. I had always wanted to be a developer (I was a compsci major). When a position opened at another division of the company I went for it.