I've got the same thing. I'm like a jet engine when it comes to energy consumption.
I would mostly recommend avoiding any types of stimulants if possible, especially caffeine (I suppose you don't do amphetamines lol). When I drink more than a half a cup a day, my metabolism seems to go haywire.
Also I've noticed over the years that everything I do I do it too hastily. I walk too fast, I think too much, I multitask too much etc. This would seem to be logically the consequence of a fast metabolism as I feel this restlessness inside. Anyway it can be dealt by mindfully noticing your behaviour and modyfing it accordingly, which means when you are "speeding" you slow down with mental effort. It's difficult in the beginning, but over time it becomes an habit and the brain adapts to the new approach you have taken. Consequently slowing down the need for fast metabolism and high-energy intake.
I have to echo much of what is said here, and shifter especially. I am trying to gain some weight right now myself, but I'm in the prime season for working in my job and am buzzing around constantly. I've been trying to pack it down, but I can't deal with too much food...combine that with the exercies routine I've been hackin', I'm developing some sick popeye arms. And I mean sick in the traditional sense, homeys. Captain ectomorph, reporting for duty.
I've just started eating much larger meals, but less often...I'm wondering if 1/2 hour cardio 5 days a week is too much for a weight gain period? I know anaerobic is most important in this scenerio, but I feel reluctant to give up cardio.