Firstly, laptop/tablet's are usually you're worst cast scenario for overclocking.
No BIOS options, can't really improve the cooling, every ratio will be locked so you're pretty much screwed to start with.
However, if you just *must* do it, I suggest removing one of the panels on the underside of the laptop/tablet and raising the unit so it sits further off the surface. This alone can help temperatures. Google a program called 'Clockgen' and see if you can find out the 'PLL' setting for your machine, if not, try selecting some and look at the 'clocks' screen till one reads out the speed of your processor. Then start bumping it up ever so slightly. Don't expect any kind of noticeable difference, you might get 10Mhz you might get 200Mhz, but I'd seriously recommend you don't even try - it's not worth it.
Build a cheap-o desktop rig with a couple of hundred quid
Pentium D805's are great overclocking chips and can be had for peanut's not the Core 2 Duo's are out.