You don't need to use flasher.

What you need to do is to install kernel-power-settings and then have a read through this thread on how to do exactly what it is you ask. It's only about 480 pages : )

I would suggest you do read it since it'll temper some of that 'I want a kernel and I want it right now' business you have happening. Just because you can overclock, doesn't mean you should, or that you even need to.

Good luck.