Several programs can do that for ya:
Coolbits - a registry hack that gives the driver options in overclocking
RivaTuner - go to
www.guru3d.com
PowerStrip - google search
NVnews
The download section there has these and others
CAUTION! When I got my m170 I used coolbits to autodetect, and I got some absurd overclocks of 535 core/1.3ghz mem. I returned back to my non-overclocked status and have been there since. Notebook graphics are imbedded in a small space with limited cooling capacity and air flow. BEWARE!
Also, if you have to ask how to overclock, THEN DO NOT TRY IT! They risks far outweigh the benefits you may get.
Cheers,
Dennis