Personally, I find it easiest to use the orthographic cameras (Top, Front and Left/Right) to position point lights exactly where I want them in an existing scene (for example, in the middle of a candle flame or a light shade). Clicking and dragging them using these cameras moves them on a fixed plane - for example, dragging a light in the Front Camera view does not alter the Z position, only X and Y. To drag along the Z axis I switch to Top or Left/Right.

So... three quick drags and everything is perfect. Make of that whatever you will. :O)

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)