This is something I am familiar with, I boxed for 6 years eating around 4k+ calories the entire time. When I stopped boxing I didn't stop eating (lol) the weight shot up 188 in a few months with no goal in mind. I barely lifted and then I decided I had to either slow down on the eating or start doing something. So I concentrated on bulking and within 3 years I go from 160 to 250 pounds. This was done with little (actually no cardio) for almost the entire time, and eating above 5k calories for several months. The hardest part for me was breaking 200, but once it was done my weight shot through the roof.
During that time I used various test boosters and proteins, and those helped with the calories (it gets hard to eat that much everyday). iForce has Protean in various delicious flavors and a variety of test boosters to help you along the way: Testabolan V2, Reversitol V2, Intimidate SRT, and Tropinol XP. These things will help but in the end it is essentially about your ability to put away a crapload of food.