M.Sc. after long 16 years in industry How hard is it to adapt to post-graduate studies after an academic pause of 16 years working in sort of relevant industry?

I graduated back in 1998 with B.Eng. in computer engineering, worked for 16 years in IT related jobs, and decided to go back to school this fall (2014).

Is it hard to be ready after such long academic pause? 
Any particular skills I should work on while waiting for the program to start?
I graduated back in 1984 with a BSc in Computer Science. Went back for a MSc by research 25 years later, in 2009. Finished that in 2011, and now I'm doing my PhD.

Will you be doing an MSc by research? If you're the sort of person who likes learning things on your own, I'm sure you'll find it easy enough to adjust. Reading scientific papers is a skill that takes a while to learn. (Writing them, even more so!) You can use Google Scholar to search for papers in the are you're interested in. (Many articles will be behind paywalls, so you probably can't access them until you start, but many articles will be freely available.) Expect it to be tough going at first, so don't get discouraged. Also, I hope you like (or at least don't mind) writing, because in many fields an MSc thesis involves a lot of writing.

If you're doing an MSc by coursework, I don't have too much advice to offer.

Your experience in industry will help you a lot. You'll probably have more resiliency than your fellow students, due to your life experience. This will help you deal with stress. You'll probably find that teachers and students are asking for your real-world perspective, which is great for your self-confidence. Also, you probably have a very clear idea of why you're doing an MSc, which will help you stay focused.