Converting single switch to 2-way

[sossage]

I have a single hall light above my stairs controlled by a switch at the top.

I would like to change this to 2-way and install a switch at the bottom of the stairs too, for obvious reasons.

Question is: -

1) How do i wire this ?
2) What's the recommended way of running cable from top to bottom as obviously cable runs should be horizontal or vertical and not at the angle of the stairs ?

Thanks in advance,
Soss.

 

[paulfromswindon]

Have a look at this:

//www.diynot.com/forums/viewtopic.php?t=3508