I for sure know how difficult it can be to put on size. I started wrestling at 15 years old, tickling the scales at only 133lbs. I knew I had to get my size up if I was to ever have a hope of making something of myself in this job. Unfortunately for me I'm the worst type of hard gainer. I get chubby very easily and still find it hard to see the weight go up! The fact is you soon learn that you have to crack a few eggs to make an omelette and if you want to gain size fast you will have to settle for getting a little 'soft' in certain areas.
Fact is calories are your friend when it comes to growing. Muscles need calories to develop. Personally I don't think your training should change much.
Often I hear people say "I'm not doing cardio because I want to get size on"
My opinion is that is the wrong approach. Cardio is always essential especially when bulking simply for your heart. A high calorie diet can have significant impact on your heart, therefore cardio is something you should still include in your workouts.
I'm not saying do intense circuits like you may do when it's time to cut up, but still look after that heart!
Still stick to certain principles, for example not eating carbs after a certain time, avoiding lots of sugar.
You will be looking at hitting around 6-8000 calories per day; so
An example of my bulking diet:
120g oats with honey and cashews nuts
3 egg whites
3 whole eggs
2 bacon medallions
Half pint of fresh orange juice
100g full fat Greek yoghurt
1 scoop protein
10g broken 70% dark chocolate
5 chicken thighs (skin on)
100g potato wedges
Veg with extra virgin oil dressing
1 sweet potato with butter/margarine
100g chocolate cereal
1 pot full fat cottage cheese
Table spoon peanut butter
Try these super calorific meals and see those gains grow!