Hi Turbolader,
I used to be a mechanical engineer. In fact, I even ran our school's Formula SAE program for a couple of years.
The usual progression to becoming a professional pilot is to get your private pilot certificate first. This will give you a good taste of what it's like to be a pilot, and then if you're still interested in making it a profession, you can continue on with your flying education.
Becoming a commercial pilot takes quite a bit of money, dedication, and hard work. The first couple of years are really low in pay (somewhere in the $23,000 range is typical). It usually goes up eventually, but it really is rough the first couple of years, particularly once you've become used to an engineering salary. I was lucky in that I had pilot jobs that paid pretty well my first two years, but that's rare and I budgeted for the low end going into this.
As far as flight training goes, don't be in a big hurry. Right now is a terrible time to be looking for work as a pilot, and will probably continue to be bad for a couple of years. Your best bet is to continue working and do pilot training on the weekends and after work. That's what I did, and it worked out really well.
I'm almost into my third year of flying as a professional pilot, and I'm really enjoying it. It's a little stressful worrying about my job with this economy, even though it's supposedly safe. I guess even if I was in engineering I'd be a little worried about my job. Anyway, if you have any questions let me know. If you tell us where you live, myself or others here can probably tell you where to get started. Good luck!