Installing an additional light switch

I want to add an additional light switch to an existing lighting circuit.

My garage has a single light in the centre, which is operated by an existing light switch on the wall by the garage door. I want to install an additional light switch by the access door to the house, which, of course, is in the far corner of the garage to the existing switch, so I can turn the light off when leaving the garage, rather than using the existing switch and then breaking my neck when trying to find my way back to the access door in the dark!

Do I have to change the existing ceiling rose to accept wiring from a second switch? Can I introduce wiring from a second switch to the exisitng rose? or do I have to connect the new switch all the way around the garage to the exisitng switch?

Could someone kindly give me some guidance.

All you need to d is run a length of 3core and earth cable from the existing switch to where you want the additional switch.
Have a look in the FAQ under two way lighting. Its all explained there.

The wiki also hase come very useful digarams.