Yeah, I guess. I don't know how to manually do this, but usually there is a utility that comes with your motherboard that allows you tweak everything out. I am not sure how much benefit you are going to see from overclocking your processor. Usually gamers are the ones overclocking so they can get as many frames per second as possible on their games (obsessively). Also, when you overclock your processor you have a higher risk of burning up your chip.
Don't do it! Overclocking is a very tricky science with a high risk of disaster. first off you need to know you have enough cooling: the out of the box cooling that's on your processor is not enough to overclock it. secondly you have to make sure you have enough power. thirdly you have to make sure you have enough money to buy a new processor, cause once it burns out you have to buy a new one (the chips contain hardware that tells the manufacturer it has been overclocked and once overclocked your warranty isn't worth the paper it's written on.)
It's true gamers frequently overclock their computers and there's tons of info out there about how to do it. the most popular way now a days is to use liquid cooling systems (a heat pump if you will) to cool the graphics card and processor. this is a tricky procedure that you should only do if you know what you're doing or if you pay someone else to do it for you. Furthermore it can be quite expensive.
The problem I've encountered with overclocked pcs and video apps like After Effects is that the application is already pushing the processor as hard as it can so once overclocked you quickly fry it. I can't quite explain how this works - I think it's because when you play a game the processor is only used at full capacity when a lot of things are going on at once and the 3d rendering is always shared between the processor and the graphics processor. but with after Effects and other video editing software all the rendering is done in your processor alone so the work load is much higher. Even in my system which has 6 fans in addition to the massive processor fan the processor sometimes gets so hot that the computer goes into "cool-down-mode" where the processor is slowed to cool down.
The best and safest way of making your computer faster is to optimize it for video editing. The easiest thing to do is go to the Videoguys.com website and do the optimizations they reccommend. you will se a massive improvement. If that's not enough upgrade your RAM (more and faster - maybe 2 or 4 gb?) and update your processor to a dual core one.