When you want to do this, you need to figure out how many calories you need in a day in order to put on quality mass. So each meal needs to be roughly 1/6 of that number. You can always divvy up the calories as needed, like a little bit more in the morning meals for the energy and a little less in the evening meals to even it out.
The meals should include a good balance of protein, carbs and fats. Yes, fats. Your body actually needs fat to survive. Some nutrients are fat soluble and need fat to travel to needed areas in the body. Fat is used for insulation and cushioning of the vital organs, but I've gone off tangent again. They, meaning nutritionists suggest that no more than 20% of the meal's calories should come from fat, meaning the remaining 80% come from protein and carbs. Low glycemic carbohydrates are a source of sustained energy because they take longer for the body to digest. High glycemic carbohydrates are a source for a quick boost of energy and are burned quickly. Stick with lean proteins, like white-meat poultry, fish or egg whites.
And yes it is really possible to eat six times a day. Think of it this way: you eat breakfast, lunch and dinner. Don't you also eat snacks? That would count as a "meal" too.
It really is possible to eat every 2-3 hours. It just takes planning on your part. At work? Prepare food in advance at home and take it to work. Out and about? Take along food that travels well. You don't have to have tupperware containers with you wherever you go, but meal replacement bars, sandwiches, bags of trail mix and mixed nuts travel well.