It can be done, not to scare you off but it is a lot more complex than Ram...
First you need to go to the laptop manufacturers site, best to do a scan to find the exact model you have if it's supported. Download and run the BIOS flashing software. - Just to cover the support aspect...Otherwise, best case scenario the laptop will show 'Unknown processor Dual whatever', worst case your machine won't boot.
The entire laptop is to be stripped (except obviously, the screen), pull the CPU out, put the new one in, I would recommend some thermal paste on the visible side of the CPU. Then replace everything.
From there, if it runs you'll probably want to run a CPU stability test for a few hours and maybe a benchmark application (Example: 3dMark) to make sure everything is running smoothly.
The best bet is to run CPU-z or EVEREST and google your laptop / motherboard. There are sites that detail what hardware is compatible with whatever machine.
There is a lot of hassle involved, but if you feel it's worth it, then it can be done! Goodluck